Iran–United States relations after 1979

Since the Iranian Revolution in 1979, the Islamic Republic of Iran has been embroiled in tense relations with the U.S. and its allies. Following the hostage crisis, both countries severed relations. Since then, both countries have been involved in numerous direct confrontations, diplomatic incidents, and proxy wars throughout the Middle East, which has caused the tense nature of the relationship between the two to be called an 'international crisis'. Both countries have often accused each other of breaking international law on several occasions. The U.S. has often accused Iran of sponsoring terrorism and of illegally maintaining a nuclear program, as well as using strong rhetoric against Israel, of which Iran has questioned its legitimacy and its right to exist while supporting Hamas, an antizionist terrorist group in the Gaza Strip. Meanwhile, Iran has often accused the U.S. of human rights violations and of meddling in their affairs, especially within the Iranian Democracy Movement.

Both countries have been in conflicts in Syria,  Iraq,  Yemen,    and Afghanistan,   supporting opposite sides and conducting operations against each other. Both countries have also to the brink of war in situations as in the Tanker War and the Persian Gulf Crisis, both of which exacerbated tensions between the two. This has caused the United States and Israel to refuse to exclude the use of force to stop Iran, although they have always stressed that they consider the use of force as a last resort.

As a result of tensions the United States has taken the opportunity to broker negotiations and alliances between Israel and Arab States, some of which have viewed Iran with antagonistic ambitions. These countries have similar views to Iran and have often cooperated with each other to achieve their goals.

During the Syrian civil war
It was reported on 30 November 2020 that an airstrike near the Iraq–Syria border killed an unidentified Islamic Revolutionary Guard Corps commander and three other men traveling with him from Iraq and into Syria. The vehicle was struck after it entered Syrian territory. Iraqi security and local militia officials said the commander's vehicle had weapons in it and that pro-Iran paramilitary groups helped retrieve the bodies. Sources did not identify the commander nor elaborate on the exact time of the incident. It was not immediately known who conducted the strike, and Reuters could not independently verify the reports.

On 10 February 2021, Pentagon Press Secretary John Kirby told reporters that U.S. troops were not committed to protecting Syrian oil fields except "for where appropriate under certain existing authorizations to protect civilians." He added that "DOD [Department of Defense] personnel or contractors are not authorized to provide assistance to any other private company, including its employees or agents, seeking to develop oil resources in northeastern Syria." However, there were reports from local sources in northeastern Syria that U.S. forces had transported oil and wheat smuggled from Syria to Iraq.

On 28 June 2021, President Biden directed airstrikes against Iran-backed militia groups close to the Syria-Iraq border. F-15E and F-16 aircraft were used to launch the attack in what the U.S. described as a retaliatory attack against U.S. facilities and personnel in Iraq by militia groups. Two operational and weapons storage facilities were targeted in Syria, the U.S. military revealed in a statement. Despite the U.S. not disclosing the information regarding the casualties in the attack, the SOHR stated that at least nine Iran-backed Iraqi militia fighters died, leaving many others injured. Iraqi militia groups aligned with Iran in a statement named four members of the Kataib Sayyed al-Shuhada faction they said were killed in the attack on the Syria-Iraq border. Hours later, U.S. forces in Syria came under fire, following the U.S. strikes on the Syria-Iraqi border. Pro-Iranian militias fired rockets at the American base at Al-Omar Oilfield in Syria in response to U.S. airstrikes. The U.S. coalition responded by firing heavy artillery on Iranian-backed Militias Positions around Al-Mayadin. There were no injuries sustained during the attack, the spokesman for Operation Inherent Resolve, Col. Wayne Marotto disclosed.

On 10 July 2021, a mortar shell landed near MSS Conoco, with no injuries reported. It was reportedly the fourth attack on or near U.S. troops or diplomats within a week, reportedly including one in which two service members were injured. No group claimed responsibility, but U.S. forces suspected Iran-backed proxy militias of carrying out such attacks.

On 20 October 2021, troops at the al-Tanf garrison were attacked by bomb-laden drones in what Pentagon spokesman John Kirby called a "complex, coordinated and deliberate attack". U.S. officials reportedly blamed Iran and its proxy forces for the attack, but publicly declined to specify details of the attack and whether the U.S. was considering retaliation. There were no reports of deaths or injuries. Attacks by small drones carrying munitions have posed a consistent threat to U.S. forces in eastern Syria since at least March 2020, with U.S. forces suspecting ISIL or Iran-backed elements of conducting the attacks, as U.S.-Iranian tensions in the region have persisted.

On 24 August 2022, Joe Biden ordered airstrikes on claimed IRGC and Russian-backed proxy groups in Syria near Deir ez-Zor. The airstrikes were in retaliation on an attack on the Al-Tanf garrison. The airstrikes were also considered a massive setback in negotiations in order to revive the JCPOA. Airstrikes were also reported on 25 August. Iran strongly condemned the strikes and denied any links with the targets. The Syrian Observatory for Human Rights claimed that Liwa Fatemiyoun and the Syrian Army were targeted in the airstrikes.

On 23 March 2023, at 1:38 p.m. local time (UTC+03:00), a kamikaze drone allegedly of Iranian origin struck a coalition base at Abu Hajar Airport near Rmelan, al-Hasakah Governorate in northeastern Syria, killing one United States contractor and injuring five servicemen and second contractor. The New York Times reported, US officials said the main air defense system at the base was "not fully operational" at the time of Thursday's Drone Strike. In retaliation, U.S. President Joe Biden authorized a response with an airstrike on IRGC-linked targets, including a weapons warehouse in the Harabish neighborhood in Deir ez-Zor, and military posts in the al-Mayadin and Abu Kamal countryside, killing 14 people including nine Syrians, according to SOHR.

On 24 March 2023, 10 rockets were launched at the Green Village near al-Omar oil field which injured another American serviceman. By afternoon, another rocket attack targeted US forces near the oil and gas fields of Conoco, east of Deir ez-Zor. On 30 March, the Pentagon revealed that twelve American were wounded in total with six U.S. troops in Syria suffering traumatic brain injuries due to the two attacks by Iran-backed militias. A little-known militant group known as Liwa Al-Ghaliboun (The Brigade of Those who Prevail) claimed responsibility for the initial drone attack, although some observers believe the group to simply be a front group for a larger Iranian-backed group or the IRGC.

On 18 October 2023, American military bases in Iraq, Iraqi Kurdistan and eastern Syria were attacked by three drones. Pentagon officials insisted that there are few casualties. On 26 October, United States DoD said it conducted airstrikes on two facilities in eastern Syria linked to IRGC-backed militias in retaliation for the attacks.

2019—2020 escalation
On 27 December 2019, Iran, Russia, and China began a four-day naval exercise in the Gulf of Oman. The exercise was launched from Chabahar Port near Pakistan, and included the Chinese Type 051 destroyer Xining. The Russian Defense Ministry confirmed it had deployed ships from the Baltic Fleet in its official newspaper Krasnaya Zvezda. According to Iranian sources, the exercise was a response to U.S.–Saudi regional maneuvers and was meant to demonstrate that Iran was not isolated. In contrast, the spokesman of the Chinese Ministry of National Defense, Senior Colonel Wu Qian claimed the exercise was a normal military exchange unconnected to the international tensions. The same day, K-1 Air Base in Iraq's Kirkuk Governorate was attacked with Katyusha rockets, injuring several Iraqi Security Forces personnel, four U.S. soldiers, and killing a U.S. civilian military contractor. U.S. Secretary of State Mike Pompeo condemned the attacks, blaming Iranian-backed Shi'ite Muslim militias, particularly on Kata'ib Hezbollah.

On 29 December, U.S. airstrikes targeted Kata'ib Hizbollah facilities in Iraq and Syria killing 25 militants and injuring at least 55 others. The Department of Defense said the operation was in retaliation for repeated attacks on Iraqi military bases hosting Operation Inherent Resolve (OIR) coalition forces, particularly the K-1 Air Base attack. About 5,000 U.S. troops were present in Iraq to deal with Islamic State of Iraq and the Levant remnants and to assist the Iraqi military. Kata'ib Hezbollah denied responsibility for the attacks.

On 31 December, after a funeral was held for the Kata'ib Hezbollah militiamen that were killed by the prior U.S. airstrikes, an angry mob of dozens of Iraqi Shiite militiamen and their supporters marched through the perimeters of Baghdad's heavily fortified Green Zone, marched down Kindi Street, and surrounded an entrance to the U.S. embassy compound. According to the Associated Press, Iraqi security forces did not attempt to stop the mob and permitted them to pass a security checkpoint. The mob began taunting American forces. An additional 100 U.S. Marines were sent to reinforce the embassy. As the fire broke out, an AP reporter on the scene observed at least half a dozen U.S. Marine Security Guardsmen and Diplomatic Security Service personnel on the roof of the main embassy building with their guns trained on the intruders, many of whom were wearing militia uniforms; the intruders stopped in a corridor after about 5 meters (16 feet), and were about 200 meters away from the main embassy building. There were also reports of tear gas being deployed to disperse the intruders as at least three protesters appeared to have difficulties breathing.

By early evening, the mob, which at one point numbered in several hundreds, had largely retreated and protesters had set up tents outside the embassy in an attempted sit-in. Kata'ib Hezbollah spokesman Jaafar al-Husseini claimed the protestors had no intention of storming the embassy and that the sit-in was to continue "until American troops leave Iraq and the embassy is closed."

Senator Lindsey Graham indicated Trump had discussed the matter of a potential attack against Qasem Soleimani with him in advance, as he was visiting the president at his Mar-a-Lago estate. According to journalist Bob Woodward, four days before the strike, Graham tried to change Trump's mind as they discussed the decision while playing golf.

On 1 January 2020, the protests flared up again as demonstrators started a fire on the roof of the reception area, reportedly prompting U.S. Marines to fire tear gas at the crowd, without any significant injuries to the protesters or guards. Iraqi soldiers, federal police, and counterterrorism units lined up between the protesters and the compound. No further clashes occurred as Popular Mobilization Forces militia leaders called on demonstrators to take down the tents and withdraw. Militia supporters considered the attack on the embassy a victory against the U.S. and that their message had been sent, with one supporter proclaiming "We rubbed America's nose in the dirt."

On 2 January, U.S. Defense Secretary Mark Esper said "the game has changed" and stated that the U.S. would preemptively strike Iranian-backed paramilitary groups in Iraq if there were indications they were preparing to attack U.S. forces, while also urging the Iraqi government to resist Iranian influence. U.S. Chairman of the Joint Chiefs of Staff Mark Milley emphasized that any group that attempted to overrun the Baghdad embassy will "run into a buzzsaw."

Early on 3 January, Qasem Soleimani arrived at Baghdad International Airport via Cham Wings Airlines. Soleimani departed from the airport alongside Abu Mahdi al-Muhandis. As their convoy was leaving the airport, an American MQ-9 Reaper loitering above struck the convoy, killing Soleimani, al-Muhandis, and 8 others. The strike had been ordered directly by American President Donald Trump, and had come hours after U.S. Secretary of Defense Mark Esper announced that the U.S. would strike if attacks were to be hinted at. Shortly after the assassination, Trump deployed an additional 3,000 troops to the Middle East, in addition to 14,000 already stationed there since May the previous year. President Trump defended the move, claiming in an interview with The Ingraham Angle on the Fox News Channel that Soleimani was planning further attacks against four U.S. Embassies across the Middle East. This was later challenged by U.S. Defense Secretary Mark Esper in interviews on Face the Nation on CBS and State of the Union on CNN, who claimed that President Trump was not embellishing that there was an Iranian threat but that he had seen no evidence that U.S. embassies were to be targeted.

On the same day of the Baghdad airport strike, an IRGC financier and key commander, Abdulreza Shahlai, was unsuccessfully targeted by U.S. drones in Yemen, which killed Mohammad Mirza, a Quds Force operative, instead. Shahlai was also responsible for the killing of five American soldiers in Karbala, Iraq on 20 January 2007. According to a Washington Post investigation, the unsuccessful operation might indicate a broader operation than previously explained, raising questions about whether the mission was designed to cripple the leadership of the IRGC or solely to prevent an imminent attack on Americans as originally stated.

Amid fears of a direct confrontation between the two nations, Trump warned Iran on 4January against attacking U.S. assets or any Americans in the region. He threatened that in the event of an Iranian attack, the U.S. would target 52 Iranian sites, including cultural sites, which represented the 52 hostages taken by Iran in 1979, and would strike "very fast and very hard". The White House officially notified the U.S. Congress about the killing of Qassem Soleimani, in accordance with the 1973 War Powers Resolution, a day after the assassination had occurred. Meanwhile, thousands of people in cities across the U.S. participated in antiwar demonstrations against a new conflict in the Middle East. On the same day, the UK sent two warships, HMS Kent and HMS Defender, to the Persian Gulf to protect their ships and citizens. The Royal Navy was deployed to accompany British-flagged ships through the Strait of Hormuz.

On 4 January, Iraqi state news reported that there had been another airstrike on a convoy of medical units of the Iraqi Popular Mobilization Forces near Camp Taji in Taji, north of Baghdad. An Iraqi Army source told Reuters the attack killed six people and critically wounded three. The PMF later said there was no senior commander in the convoy, and the Imam Ali Brigades denied reports of the death of its leader. The PMF also denied that any medical convoy was targeted at Taji. There was no information about who conducted the attack. Spokesman for Operation Inherent Resolve Colonel Myles B. Caggins III said the coalition did not do it, while Iraq's Joint Operations Command denied reports of any such attack occurring, saying it was simply a false rumor that spread quickly due to the prior airport strike.

On 5 January, Iran announced that it would not continue to abide by the limitations mentioned in the 2015 nuclear deal. An Iranian government statement on state television said "If the sanctions are lifted ... the Islamic Republic is ready to return to its obligations." Iran also demanded the Iraqi parliament to get rid of the American presence in their country. The Iraqi parliament passed a resolution to expel all foreign, particularly U.S., troops from Iraqi territory through a vote boycotted by Sunni and Kurdish representatives. The media initially reported that the U.S. would comply with the resolution after a draft letter from Brigadier General William H. Seely III addressed to the Iraqi Defense Ministry emerged claiming as such, but Chairman of the Joint Chiefs of Staff Mark Milley and Secretary of Defense Mark Esper soon clarified that the letter had been sent in error and the U.S. Armed Forces would not withdraw from Iraq. In response to the Iraqi parliament situation, Trump threatened to impose sanctions on Iraq "like they've never seen before".

Al-Manar reported that "in an extraordinary session on Sunday (5 January), 170 Iraqi lawmakers signed a draft law requiring the government to request the withdrawal of U.S. troops from Iraq. Only 150 votes are needed that the draft resolution be approved." There are 329 lawmakers in total. Rudaw Media Network (Kurdish) described the 170 Iraqi lawmakers that signed the law as Shiite and that "Iraqi parliament's resolution to expel foreign troops has no legal consequences." Al Jazeera reported the resolution read "The government commits to revoke its request for assistance from the international coalition fighting Islamic State due to the end of military operations in Iraq and the achievement of victory" and "The Iraqi government must work to end the presence of any foreign troops on Iraqi soil and prohibit them from using its land, airspace or water for any reason." The resolution was approved in the Iraqi parliament. In response to the vote, Trump threatened Iraq with sanctions that would "make Iranian sanctions look somewhat tame" and demanded reimbursement for American investments on military facilities in Iraq.

As the funeral procession for Soleimani and al-Muhandis was ongoing in Baghdad, several rockets hit near the U.S. embassy and the Balad Air Base without any casualties.

On 6 January, the Pentagon released a letter from Marine Brigadier General William Seely to Abdul Amir, the Iraqi deputy director of Combined Joint Operations Baghdad, informing him that "as requested by the Iraqi Parliament and the Prime Minister, CJTF–OIR will be repositioning forces over the course of the coming days and weeks to prepare for onward movement." Shortly afterward, Chairman of the Joint Chiefs of Staff Mark Milley said, "That letter is a draft. It was a mistake, it was unsigned, it should not have been released... [it was] poorly worded, implies withdrawal, that is not what's happening." On 6January, Chevron evacuated all its American oil workers from Iraqi Kurdistan as a "precautionary measure".

On 7 January, Iran's parliament approved a €200 million increase in the Quds Force's budget, to be used in two months. Iran's parliament also voted to declare the United States Armed Forces to be a terrorist organization.

On 8 January, Iraq's Al Asad Airbase, which hosts U.S.-led coalition troops, was attacked with ballistic missiles as a part of Iran's "Operation Martyr Soleimani", named for general Qasem Soleimani. It was also reported that the airbase in Erbil in Iraqi Kurdistan was attacked as well. During the attack, the IRGC declared that "fierce revenge by the Revolutionary Guards had begun", indicating it was the official response to the killing of Soleimani. Ali Khamenei, the Supreme Leader of Iran, said military actions are not enough and that the "corruptive presence" of the U.S. in the Middle East must be ended. Khamenei also described the attacks as a "slap in the face" to the U.S. Khamenei later reiterated this during a Friday sermon on 17 January, describing the attack as showing that "Iran has the power to give such a slap to a world power shows the hand of God". In a speech broadcast on Iranian television IRINN TV, Iranian President Rouhani stated that Iran will no longer stick to the 2015 nuclear agreement restrictions on uranium enrichment: "Iran's nuclear industry will prosper" he said. Rouhani also mentioned in his speech that "They cut off the hand of our dear Soleimani" and as revenge they, the Iranians, would cut off the legs of the Americans and toss them out of neighboring countries.

During his White House address hours after the attack, Trump ruled out a direct military response, urged rapprochement with Iran, demanded NATO be more involved in regional affairs, and demanded a new Iran nuclear deal be arranged. Trump, however, also announced new sanctions on Iran and affirmed his position that Iran could not be allowed to develop nuclear weapons.

Hours after the ballistic missile attacks, Ukraine International Airlines Flight 752 was shot down and crashed after taking off from Tehran International Airport, killing all 176 passengers and crew, including 82 Iranian and 63 Canadian citizens. An investigation was launched to decipher the reason for the crash. Canadian Prime Minister Justin Trudeau urged deescalation and claimed that the United States' escalation of the conflict was partially to blame for the accident, saying "If there was no escalation recently in the region, those Canadians would be right now home with their families. This is something that happens when you have conflict and the war. Innocents bear the brunt of it." The incident slightly worsened Canada–United States relations. The airline shoot-down also reignited anti-government protests within Iran that had previously become dormant during the massive public outcry against the death of Soleimani. Foreign ministers from the countries who lost citizens in the crash—Canada, Ukraine, Sweden, Afghanistan, and the United Kingdom—met at the Canadian High Commission in London and demanded that Iran provide compensation for families of the victims.

On 9January, U.S. Ambassador to the United Nations Kelly Craft sent a letter to the U.N. Security Council announcing that the United States was willing to negotiate with Iran to prevent further escalation. Ayatollah Khamenei rejected the possibility of talks at any level between U.S. and Iranian officials unless the United States returned to the JCPOA; Iranian Permanent Representative to the United Nations Majid Takht-Ravanchi likewise rejected the option. Both ambassadors justified their countries' military actions under Article 51 of the United Nations Charter. Meanwhile, U.S. officials said they believed the aircraft had been shot down in error by an Iranian Tor missile, based on evidence from reconnaissance satellite imagery and radar data.

On 10 January, Acting Prime Minister Adil Abdul-Mahdi called Secretary of State Pompeo demanding that the U.S. send a delegation "to prepare a mechanism to carry out the parliament's resolution regarding the withdrawal of foreign troops from Iraq". Pompeo rejected Prime Minister Abdul-Mahdi's requests. Shortly afterwards Iraq's highest-ranking Shia cleric, Grand Ayatollah Ali al-Sistani, condemned the U.S.–Iran crisis. The Trump administration, meanwhile, imposed new economic sanctions targeting Iran's metals industry and eight senior officials who were involved in the prior missile attacks. According to U.S. Secretary of the Treasury Steven Mnuchin, the sanctions would affect "billions" in revenue. The U.S. also warned Iraq that it would freeze its account at the Federal Reserve Bank of New York if it continued to urge the withdrawal of American troops, which would prevent the Iraqi government from accessing oil revenues, damage the Iraqi economy, and devalue the Iraqi dinar.

On 11 January, Iranian officials admitted to accidentally shooting down Flight 752. Following the announcement, two thousand people protested in Tehran, with chants including "Death to the dictator". Police used tear gas on the protestors. Officials reported that 82 Iranians among several other Iranians with dual citizenship were among the victims of the crash. Two hundred people protested in front of Amirkabir University of Technology. The protestors called for the Supreme Leader Ali Khamenei to resign, chanted "Death to the liars" and called "for the IRGC to leave the country". Protests also took place at the Sharif University of Technology and in Amol, Isfahan, Rasht, Sari, and Hamedan. Protesters chanted against the Revolutionary Guards, the Supreme Leader, and the entire political system of the Islamic Republic.

On 12 January, Hezbollah Secretary-General Hassan Nasrallah called for Iran's allies in the Axis of Resistance—including Iran, the Syrian Arab Republic, Hezbollah, the Popular Mobilization Forces, and the Houthi movement in Yemen—to intensify its military campaigns against the U.S. to expel U.S. forces from the Middle East.

On 14 January, British Prime Minister Boris Johnson encouraged the negotiation of a new nuclear deal between the Trump administration and the Iranian government, which President Trump expressed agreement with.

On 15 January, the United States and Iraq resumed joint military operations against the Islamic State after a ten-day suspension following the drone strike on Soleimani.

On 17 January, Ayatollah Khamenei personally led Friday prayers in Tehran for the first time since February 2012, speaking at the Imam Khomeini Grand Mosque. During his televised sermon, Khamenei lamented the shootdown of the Ukrainian airliner, sought to present the image that the country was unified despite protests and the international crisis, and lashed out at the UK, France, and Germany, referring to them as "servants" of the "villainous" United States. Khamenei denounced the Trump administration as "clowns" and insisted that the "real punishment" for General Soleimani's assassination would be forcing American forces out of the Middle East. In response Trump, who was vacationing at Mar-a-Lago resort in Palm Beach, Florida, at the time, made posts on Twitter urging Iranian leadership to stop "killing" Iranian protesters and that it "should abandon terror and Make Iran Great Again!" One of the posts was written in both English and Persian. On the same day, the Asian Football Confederation banned Iran from hosting international football matches. On 18 January, the U.S. sanctioned Brigadier General Hassan Shahvarpour, an IRGC commander in Khuzestan Province, after security personnel fired into protesters without warning during anti-government demonstrations in Mahshahr County.

History of proxy warfare
The United States and Iran have used proxy warfare throughout the Middle East and the Arab World since the 1979 Iranian Revolution.

The first instance of proxy warfare came during the Iran–Iraq War, when Iraq used American support to fight the war. However, American views toward Iraq were not enthusiastically supportive in its conflict with Iran, and activity in assistance was largely to prevent an Iranian victory. This was encapsulated by Henry Kissinger when he remarked, "It's a pity they both can't lose."

In February 1982, Iraq was removed from the State Department's list of State Sponsors of Terrorism to ease the transfer of dual-use technology to that country. According to investigative journalist Alan Friedman, Haig was "upset at the fact that the decision had been made at the White House, even though the State Department was responsible for the list." "I was not consulted," Haig is said to have complained. In March, President Reagan signed National Security Study Memorandum (NSSM) 4-82—seeking "a review of U.S. policy toward the Middle East"—and in June Reagan signed a National Security Decision Directive (NSDD) co-written by Teicher, who was now at the NSC, which determined: "The United States could not afford to allow Iraq to lose the war to Iran."Pursuant to this Directive, Thomas Twetten arrived in Baghdad on July 27 to share CIA satellite imagery on Iranian troop movements with the Iraqi Mukhabarat. This was "the first U.S. provision of intelligence to Iraq," and sparked a short-lived debate over whether Iraq would tolerate a CIA presence in the country: Mukhabarat head Barzan Tikriti told Twetten to "get the hell out of Iraq," but Iraqi military intelligence—"having already drooled over it and having said repeatedly how valuable it was"—subsequently informed Twetten "we'll continue to look at your information, and we'll assess whether it is of use to us in any way." Reports of Iraq's use of chemical weapons against Iran reached the CIA as early as 1983, but the U.S. took no action to restrain Iraq's violations of international law, failing even to alert the UN. By November 1983, the State Department had been briefed on Iraq's "almost daily use of [chemical weapons]". In late 1983, Ronald Reagan selected Donald Rumsfeld as his envoy to the Middle East; Rumsfeld met Saddam in Baghdad in December 1983 and March 1984. "On November 26, 1984, Iraq and the U.S. restored diplomatic relations." The U.S. reportedly sought to normalize relations with Iraq in late 1983, but Saddam did not agree until 1984. The United States has also backed the People's Mojahedin Organization of Iran, a group that had actively participated against Khomeini's government in Iran.

During the deployment of American troops in Lebanon during the Lebanese Civil War as part of the Multinational Force in Lebanon, Hezbollah, under the umbrella Islamic Jihad Organization, carried out attacks against American and Israeli troops in Lebanon with Iranian support, including the 1983 United States embassy bombing in Beirut and the Beirut barracks bombing. The U.S. maintains that the bombings were carried out with Iranian support.

In the aftermath of the 2003 invasion of Iraq, Iran supported Shi'ite insurgent groups dubbed the Special Groups in Iraq, which were made up by the Mahdi army, Kata'ib Hezbollah, Asa'ib Ahl al-Haq, and the Promised Day Brigade. The U.S. used the Iraqi government to fight these insurgents as a result.

Iran and the United States engaged once again in proxy warfare during the Arab Spring, mainly in Syria following an uprising against pro-Iranian dictator Bashar al-Assad. Iran sought its proxy forces to support and aid Assad's government, seeing it as crucial for its interests. Meanwhile, the U.S., Turkey, Qatar, and Saudi Arabia supported the uprising, with the latter three funding revolutionary groups. Following the escalation of the conflict into civil war, the conflict became subsumed into a proxy war between Russia and the United States, with Russia largely supporting Iranian efforts in Syria to contain rebels. Iran, Russia, and Syria, alongside Hezbollah and Iraq, formed a military coalition, of which was viewed by the U.S. as an attempt by said countries to antagonize the West.

Iran and the U.S. also engaged in proxy warfare in Yemen, where the U.S. supported the Saudi Arabian–led intervention in Yemen. The U.S. officially intervened in October 2016 after the Houthis attacked a United States Navy ship. Iran has supported the rebel Houthis, while the Saudi coalition supported the government of Abdrabbuh Mansur Hadi.

While not confirmed, the U.S. maintains that Iran supported the Taliban during the War in Afghanistan, Multiple Sources:
 * Iran still supporting Afghan insurgency-U.S. Reuters 23 November 2010
 * Iran accused of supporting Afghan insurgents
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * Iran still supporting Afghan insurgency-U.S. Reuters 23 November 2010
 * Iran accused of supporting Afghan insurgents
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * Iran still supporting Afghan insurgency-U.S. Reuters 23 November 2010
 * Iran accused of supporting Afghan insurgents
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * Iran still supporting Afghan insurgency-U.S. Reuters 23 November 2010
 * Iran accused of supporting Afghan insurgents
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * Iran still supporting Afghan insurgency-U.S. Reuters 23 November 2010
 * Iran accused of supporting Afghan insurgents
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * Iran still supporting Afghan insurgency-U.S. Reuters 23 November 2010
 * Iran accused of supporting Afghan insurgents
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * Iran accused of supporting Afghan insurgents
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.
 * and also assessed that Iran paid bounties to the Taliban splinter group known as the Haqqani network.

Proxy warfare between the two intensified throughout the 2020s, after Iran began backing Russia with weaponry amidst the latter's invasion of Ukraine,   which has led to Ukrainian condemnation. The United States has provided aid for Ukraine on the other hand. During the 2023 Israel–Hamas war, both Iran and the United States supported opposite sides, with Iran allegedly helping plan the Hamas incursion into Israel while the U.S. has backed Israel.

Diplomatic activity linked to Iranian nuclear program
The Iranian nuclear program has been controversial as, although the development of a civilian nuclear power program, including enrichment activities, is explicitly allowed under the terms of the Nuclear Non-Proliferation Treaty (NPT), there have been allegations that Iran has been illicitly pursuing a nuclear weapons program, in violation of the NPT (see Iran and weapons of mass destruction).

Under the leadership of the United States and of the European Union, the international community has requested the end of enrichment activities in Iran. The 118 member states of the Non-Aligned Movement however have backed Iran's right to "acquire peaceful nuclear technology".

This diplomatic effort culminated in United Nations Security Council Resolution 1737, adopted (after a significant amount of diplomatic efforts) with the approval of both China and Russia (which held veto power). This resolution imposes specific, but light, economic sanctions solely linked to Iran's nuclear program.

The resolution mentions that in the event that "Iran has not complied with this resolution, [the security council will] adopt further appropriate measures under Article 41 of Chapter VII of the Charter of the United Nations to persuade Iran to comply with this resolution and the requirements of the IAEA, and underlines that further decisions will be required should such additional measures be necessary." According to the resolution, Iran must comply within 60 days, i.e. before 20 February 2007.

Iran has strongly rejected this resolution. Iran's parliament passed a bill on 27 December 2006 obliging the government to "revise" its cooperation with the International Atomic Energy Agency and to accelerate its drive to master nuclear technology in a reaction to the U.N. resolution. The bill gave President Mahmoud Ahmadinejad's government a free hand to adopt a tougher line against the IAEA, including ending its inspections of Iran's atomic facilities.

On March 2, 2007, six key nations, including the 5 permanent members of the UN Security Council, which hold veto power, have agreed to pass a new resolution to impose tougher sanctions on Iran regarding its nuclear issue at the United Nations Security Council, French Foreign Minister Philippe Douste-Blazy said.

In March 2007, Russia announced that construction of a nuclear reactor would be delayed at least two months because Iran had failed to make monthly payments since January. It said the delay could cause "irreversible" damage to the project. Because of the delay, Russia also indefinitely put off the delivery of enriched uranium fuel it had promised to provide Iran in March. Iran, which denied falling behind in payments, was furious, convinced Russia was pressuring the country to bend to the U.N. Security Council, which has placed sanctions against it for refusing to suspend uranium enrichment. The pattern of Russia's behavior has strengthened Iran's determination to obtain the full technology to build nuclear power plants and end its dependence because they say Russia has never been and will never be a reliable partner.

Accusation of hypocrisy and double standards by Iran toward the West
On February 20, 2007, before the expiration of the United Nations Security Council deadline asking Iran to suspend uraninium enrichment, Ali Larijani, Iran's Head of the National Security Council, warned that “double standards will severely damage the credibility of international bodies“. “I think certain countries are seeking adventure on Iran’s nuclear case. You know that some countries until now have not signed the NPT, but are conducting nuclear activities,“ he said, regretting that no action has been taken against such countries while the UN Security Council has passed a resolution against Iran.

On March 18, 2007, Iran, under fire from Western powers over its atomic program, criticized Britain's plans to renew its nuclear arsenal as a "serious setback" to international disarmament efforts. Britain's parliament backed Prime Minister Tony Blair's plans to renew the country's Trident missile nuclear weapons system.

"Britain does not have the right to question others when they're not complying with their obligations" referring to the obligation by the U.K., United States, Russia and France to disarm under the NPT accord and "It is very unfortunate that the UK, which is always calling for non-proliferation not only has not given up the weapons but has taken a serious step toward further development of nuclear weapons," Iran's envoy to the International Atomic Energy Agency, told a conference examining the Trident decision.

In a Question and Answer session following his address to Columbia University on September 24, 2007, the Iranian President remarked: "I think the politicians who are after atomic bombs, or testing them, making them, politically they are backward, retarded."

Opposition inside Iran to nuclear energy policy
On 20 February 2007, a small radical reformist political party, the Islamic Revolutionary Mujahadin Organisation, complained that Iran's drive to produce nuclear energy has endangered national security, the national interest and the destiny of the Iranian people.

On 26 February 2007, the conservative daily Resalat chided Ahmadinejad, saying "neither weakness nor unnecessarily offensive language is acceptable in foreign policy."

Iran and Israel
Iranian leaders have made vehement declarations against Israel. Ahmadinejad was widely reported as calling for Israel to be "wiped off the map." However, this translation is disputed, and some have considered it a psyop. A call for Israel's destruction is also attributed to Ayatollah Khomeini, the political leader of the 1979 Islamic Revolution., and Iranian military parades featured ballistic missiles adorned with slogans such as 'Israel must be uprooted and erased from history'.

The Iranian government has stressed they did not call for an attack on Israel. Rather, they wish to allow Palestinian refugees to return to Palestine, whereupon all inhabitants will vote on its political future. These "clarifications" are seen in Israel as a diplomatic smokescreen.

"For many long years, we have followed Iran's efforts to acquire nuclear weapons, in the guise of a civilian nuclear program," said Prime Minister of Israel Ehud Olmert.

In November 2003, Israel's defence minister Shaul Mofaz has made what sources have described as a warning of "unprecedented severity." Mofaz set out his government's position last week during a visit to the United States stating that "under no circumstances would Israel be able to tolerate nuclear weapons in Iranian possession".

Iran has also been known to use the pejorative terms Zionist entity and Little Satan, as well as calling Israel 'cancer'.

Iranian support of Islamism
According to both the United States Department of Defense and Department of State, Iran has arbitrarily funded armed militant groups throughout the Muslim World, many of which adhere to Islamism. As a result of support for several designated terrorist group such as Hezbollah, Hamas, the Taliban, and the Palestinian Islamic Jihad, the U.S. has designated Iran as a state sponsor of terror. Iran has also allegedly forged ties with al-Qaeda and thus supported the September 11 attacks and its perpetrators according to the 9/11 Commission.

The extent of Iran's support to Islamist and terrorist groups has been subject to debate, however, it is known that Iran has supported mainly anti-American groups such as Hezbollah,     rejectionist groups in Palestine such as Hamas,  the Islamic Jihad Movement in Palestine, and others,   as well as other groups including the Popular Mobilization Forces,   several Bahraini militias,    the Houthis,  and the Taliban that together form the Axis of Resistance alongside the Iraqi, Syrian, and Russian governments. Iran uses the axis of resistance as a proxy force, fighting in Lebanon, Syria, Yemen, and Iraq, and with militias collaborating with one another.

Syria
Within Syria itself, Iran uses the Axis of Resistance as a proxy force in order to support the regime of despot Bashar al-Assad. Assad and Iran hold close ties, in part due to their anti-American stance. Iran aided Syria in their crackdown of the Syrian revolution, and eventually sent troops to support the government.

Iran uses Hezbollah as a proxy within Syria, using them to attack enemies such as Israel, Turkey, and rebels. Iran and Hezbollah have both also created, funded, and armed several paramilitaries and militias within Syria loyal to the Assad Regime, as well as overseeing the involvement of other militias from Iraq, Palestine, and Lebanon. Iran also formed militias for fighters from Afghanistan and Pakistan, under the banners of Liwa Fatemiyoun and Liwa Zainebiyoun.

Iraq
Iran has been heavily involved in Iraq since the 2003 invasion that toppled Saddam Hussein from power. Iran has often used Shia militias within Iraq to disrupt American operations, while also directly participating in the insurgency that followed the invasion. Iran mainly funded the Mahdi Army, a group led by Muqtada al-Sadr. Iran has also been heavily involved with the founding of the Popular Mobilization Forces and their effort to fight the Islamic State within Iraq, fighting alongside them and the axis of resistance.

Afghanistan
In August 2020, U.S. intelligence officials assessed that Iran offered bounties to the Taliban-linked Haqqani network to kill foreign servicemembers, including Americans, in Afghanistan. U.S. intelligence determined that Iran paid bounties to Taliban insurgents for the 2019 attack on Bagram airport. According to CNN, Donald Trump's administration has "never mentioned Iran's connection to the bombing, an omission current and former officials said was connected to the broader prioritization of the peace agreement and withdrawal from Afghanistan."

Palestinian territories
Iran is known to fund several Palestinian militant groups, many of them members of the Alliance of Palestinian Forces. These groups, all of them espousing Anti-Zionism, are known to attack Israeli civilians within Israeli territory and are known to use terrorism. Iran itself has also been directly involved in several conflicts against Israel, including in 2018 and 2023.

Hamas is the main proxy group funded and armed by Iran, based in the Gaza Strip, of which it governs. It has engaged Israeli forces in direct combat several times in Gaza, with it also being notorious for its antisemitism and attacks against Israeli civilians. Alongside Hamas, Iran is also known to fund Hamas-allied Palestinian Islamic Jihad,  the Popular Front for the Liberation of Palestine, the Democratic Front for the Liberation of Palestine, and the Sabireen Movement, all of which are based in the Gaza Strip and have engaged Israeli forces. Iran also formerly supported the Popular Resistance Committees up until 2013, when relations were ruptured following the PRC's support of the Syrian opposition.

The Popular Front for the Liberation of Palestine – General Command and Free Palestine Movement, based in Syria, are also known to receive aid from Iran and the Syrian government.

Sanctions against Iran
Since the 1979 revolution in Iran, the country has been under constant US unilateral sanctions. The first U.S. sanctions against Iran were formalized in November 1979, and during the hostage crisis, many sanctions were leveled against the Iranian government. By 1987 the import of Iranian goods into the United States had been banned. In 1995, President Clinton issued Executive Order 12957, banning U.S. investment in Iran's energy sector, followed a few weeks later by Executive Order 12959 of May 9, 1995, eliminating all trade and investment and virtually all interaction between the United States and Iran. For details of current US sanctions, see the page of US Treasury.

Iran and the United States have had no formal diplomatic relations since April 7, 1980. Instead, Pakistan serves as Iran's protecting power in the United States, while Switzerland serves as the United States' protecting power in Iran. Contacts are carried out through the Iranian Interests Section of the Pakistani Embassy in Washington, D.C., and the US Interests Section of the Swiss Embassy in Tehran. In August 2018, Supreme Leader of Iran Ali Khamenei banned direct talks with the United States.

The United States have not been followed yet by other countries. But the UN sanctions are the first international sanctions levied on Iran. The United States is pushing for more economic sanctions against Iran. Under a proposal by Germany, which holds the EU presidency during the first semester of 2007, the European Union is also considering imposing sanctions that go beyond the UN sanctions but has not made any decision yet.

In June 2007 leading EU countries including Britain, France and Germany cautioned Iran that it faces further sanctions for expanding uranium enrichment and curbing U.N. inspectors' access to its nuclear program. "Iran continues to ignore its obligations and has not taken any steps to build confidence in the exclusively peaceful nature of its program". Additionally, the EU offers Iran suspension of sanctions and a package of trade and industrial benefits if it suspends its nuclear program.

The Iran Sanctions Enhancement Act of 2007 introduced by Representatives Mark Kirk and Rob Andrews would've threatened sanctions against any company or individual that provided Iran with refined petroleum products or engaged in an activity that could have contributed to the enhancement of Iran's ability to import refined products after 31 December 2007. The bill could have led to sanctions against gasoline brokers, tankers and insurers, but never passed.

On September 22, 2022, the United States Department of the Treasury announced sanctions against the Iran Morality Police as well as seven senior leaders of Iran's various security organizations, "for violence against protestors and the death of Mahsa Amini". These include Mohammad Rostami Cheshmeh Gachi, chief of Iran’s Morality Police, and Kioumars Heidari, commander of the Iranian army's ground force, in addition to the Iranian Minister of Intelligence Esmail Khatib, Haj Ahmad Mirzaei, head of the Tehran division of the Morality Police, Salar Abnoush, deputy commander of the Basij militia, and two law enforcement commanders, Manouchehr Amanollahi and Qasem Rezaei of the LEF in Chaharmahal and Bakhtiari province of Iran. The sanctions would involve blocking any properties or interests in property within the jurisdiction of the US, and reporting them to the US Treasury. Penalties would be imposed on any parties that facilitate transactions or services to the sanctioned entities.

Alleged preparations for war
United States and Israel have refused to exclude the use of force to stop the Iranian nuclear program. They have, however, always stressed that they consider the use of force as a last resort.

Starting in 2005, several analysts, including journalist Seymour Hersh, former UN weapons of mass destruction inspector in Iraq from 1991 to 1998, Scott Ritter, Joseph Cirincione, director for non-proliferation at the Carnegie Endowment for International Peace, Professor at the University of San Francisco and Middle East editor for the Foreign Policy in Focus Project, Stephen Zunes claimed that the United States planned a military attack against Iran.

Dec 19, 2006: According to CBS News report, the Pentagon is planning to bolster its presence in the Persian Gulf as a warning to Iran's continuously defiant government. CBS News national security correspondent David Martin says the U.S. military build-up, which would include adding a second aircraft carrier to the one already in the Gulf, is being proposed as a response to what U.S. officials view as an increasingly provocative Iranian leadership.

Dec 22, 2006: US Defense Secretary Robert Gates said that an increased US naval presence in the Persian Gulf is not a response to any action by Iran but a message that the United States will keep and maintain its regional footprint "for a long time."

Jan 6, 2007, a news agency reported that Israeli military sources had revealed a plan to strike the enrichment plant at Natanz using low-yield nuclear "bunker-busters." The disclosure may have been done to increase pressure on Iran to cease enrichment activities. The Israeli government denied this report. In Tehran, Iran's Foreign Ministry spokesman Mohammad Ali Hosseini told a news conference that the newspaper report "will make clear to the world public opinion that the Zionist regime is the main menace to global peace and the region." He said "any measure against Iran will not be left without a response and the invader will regret its act immediately.".

Jan 11, 2007: Administration officials said that the battle group would be stationed within quick sailing distance of Iran, a response to the growing concern that Iran is building up its own missile capacity and naval power, with the goal of military dominance in the Gulf.

Jan 12, 2007: President Bush accused Iran in a speech this week of helping launch attacks against U.S. troops in Iraq. His remarks were followed by combative comments from his top war advisors, new moves by U.S. naval forces and a raid Thursday in the Kurdish-controlled city of Irbil. The administration moved Friday 12 January to defuse concerns that it was planning or inviting a confrontation with Tehran. At a news conference, White House Press Secretary Tony Snow dismissed as an "urban legend" suggestions that the United States was preparing for another war. Similar denials were issued by Defense Secretary Robert M. Gates and Marine Gen. Peter Pace, chairman of the Joint Chiefs of Staff.

Jan 14, 2007: A former Russian Black Sea Fleet Commander, Admiral Edward Baltin, says he believes the presence of so many US nuclear submarines in the Persian Gulf meant a strike was likely.

Jan 24, 2007: Iranian officials said Wednesday that they had received a delivery of advanced Russian air defense systems that are designed to protect its nuclear facilities at Isfahan, Bushehr, Tehran, and eastern Iran from attack, primarily from Israeli or American aircraft.

Feb 18, 2007: According to Scott Ritter, who reiterated his view that Iran will be attacked by Feb 18, 2007: According to Scott Ritter, who reiterated his view that Iran will be attacked by the US, the Pentagon has negotiated basing rights in Romania and Bulgaria so that B-1 and B-2 bombers can operate out of airfields there.

Jul 6, 2009: It was reported that Joe Biden gave a green light to Israel for a military attack on Iran, however it was a misunderstanding, no green light was given to attack.

Opposition to potential war
Organized opposition to a possible future military attack against Iran by the United States is known to have started in 2005. Beginning in early 2005, journalists, activists, and academics such as Seymour Hersh, Scott Ritter, Joseph Cirincione, and Jorge E. Hirsch began publishing claims that American concerns over the alleged threat posed by Iran's nuclear program might lead the US government to take military action against that country in the future. These reports, and the concurrent escalation of tensions between Iran and some Western governments, prompted the formation of grassroots organisations, including Campaign Against Sanctions and Military Intervention in Iran in the US and the United Kingdom, to advocate against potential military strikes on Iran. Additionally, several organizations and individuals, including the Director-General of the International Atomic Energy Agency, Mohamed ElBaradei, a former United Nations weapons inspector in Iraq, Scott Ritter, the Non-Aligned Movement of 118 states, and the Arab League, have publicly stated their opposition to a would-hypothethical attack on Iran.