International aid to combatants in the Iran–Iraq War

During the Iran–Iraq War, both Iran and Iraq received large quantities of weapons.

Military support
Support for Iran was divided. Following the Iranian Revolution, as many as 14,000 military commanders and officers were imprisoned, executed, purged or discharged under charges of being loyal to the deposed Shah and treason for a failed coup to topple the Islamic Republic. Many trained engineers had also either fled the country or were forced to serve in their hometown, which had no use for their expertise. This had massively weakened Iran's army, leaving it incapable of protecting Iran's borders. Around this time, Iraq's leader, Saddam Hussein, decided was the perfect opportunity to launch an all-out invasion against Iran. Iran, therefore, created a new branch of military, called the IRGC, which was initially tasked with fighting and shutting off numerous separatist groups formed and armed around Iran. Following the Iraqi invasion, the IRGC then expanded its field of operations to fighting Saddam's forces. The army, which was equipped with Western weaponry, was not prepared to defend Iran and so much of Iran's Western ammunition and heavy equipment were left unusable as the army was recovering. So the IRGC, tasked its first member, Mohsen Rafighdoost, with purchasing arms from the Eastern Bloc. Rafighdoost contacted and established positive ties with many countries including Syria (under Hafez al-Assad), Libya (under Gaddafi), North Korea (under Kim Il Sung), Bulgaria (under Todor Zhivkov), Poland, Yugoslavia, East Germany, China (under Deng Xiaoping) and eventually the Western Bloc (after Switzerland who indirectly sold Iran western ammunition, Argentina also reached out to Iran proposing arms sales and agreed to also train Iranians in TOW production) to purchase arms for the IRGC. Iran's recovering army, however, had its own logistics support who reached out to Western Bloc countries including the United States and, indirectly, Israel to purchase ammunition and spare parts for their Western-made military equipment. Syria, Libya (who supplied Iran with approximately US$900 million dollars worth of free arms and 30 Scud-B missiles and North Korea (who later supplied Iran with between 200 and 300 Soviet-built Scud-B and Scud-C missiles and transferred missile production technology to Iran) were the first suppliers of arms to Iran. Eastern Bloc followed suit under financial pressures as the Soviet Union no longer had strict policies on sanctioning Iran. Rafighdoost maintains that the equipment Iran received from the United States following the Iran-Contra affair, were non-functional and broken which were made usable after repairs. He was also contacted by a third-party with ties to Switzerland who agreed to provide Iran with Western-made ammunition. Rafighdoost also claims that he was approached by an Israeli arms dealer in his hotel room while he was in Switzerland, and he rejected him.

Iran was also backed by the Kurdish parties of KDP, and PUK, also the Islamist Kurdish Mujahideen in North Iraq, all organizations in fact rebelling against Iraqi Ba'athist government with Iranian support.

Logistic support
Iran's foreign supporters gradually came to include Syria, Libya and South Yemen, through which it obtained Scud missiles. It purchased large quantities of weaponry from North Korea and China, notably the Silkworm anti-ship missile. It also acquired arms from Portugal, notably after 1984. It also acquired propellants and other weapons related components from Spain and Portugal. The United States also provided covert support for Iran through Israel, although it is debated as to whether U.S. President Ronald Reagan ordered the sale of weapons to Iran. Most of this support included TOW missiles.

Military support
Iraq was supported by the People's Mujahedin of Iran, an armed group of Iranians opposing the Islamic Republic of Iran.

Logistic support
Iraq's army was primarily equipped with weaponry it had previously purchased from the Soviet Union and its satellites in the preceding decade. During the war, it also purchased billions of dollars' worth of advanced equipment from France, China, Egypt, Germany and other sources. Iraq's three main suppliers of weaponry during the war were the Soviet Union followed by China and then France.

The United States sold Iraq over $200 million in helicopters, which were used by the Iraqi military in the war. These were the only direct U.S.-Iraqi military sales. At the same time, the U.S. provided substantial covert support for Saddam Hussein. The CIA directed non-U.S. origin hardware to Saddam Hussein's armed forces, "to ensure that Iraq had sufficient military weapons, ammunition and vehicles to avoid losing the Iran-Iraq war." And "dual use" technology was transferred from the U.S. to Iraq.

West Germany and United Kingdom also provided dual use technology that allowed Iraq to expand its missile program and radar defences.

According to an uncensored copy of Iraq's 11,000-page declaration to the U.N., leaked to Die Tageszeitung and reported by The Independent, the know-how and material for developing unconventional weapons were obtained from 150 foreign companies, from countries such as West Germany, the U.S., France, UK and China.

Iraq's main financial backers were the oil-rich Persian Gulf states, most notably Saudi Arabia ($30.9 billion), Kuwait ($8.2 billion) and the United Arab Emirates ($8 billion).

The Iraqgate scandal revealed that branch of Italy's largest bank, Banca Nazionale del Lavoro, in Atlanta, US, relying largely on U.S. taxpayer-guaranteed loans, funneled $5 billion to Iraq from 1985 to 1989.