International day of mourning

An international day of mourning is a day, or one of several days, marked by mourning and memorial activities observed among countries under an intergovernmental organization. They are designated by the intergovernmental organization. Such days include those marking the death or funeral of a renowned individual or individuals from a country of that organization or elsewhere or the anniversary of such a death or deaths, the anniversaries of a significant natural or man-made disaster occurring in the country of the organization, wartime commemorations or in memory of the victims of a terrorist attack. Common symbols include flying the organization's flag at half-mast and observing minutes of silence.

Background
The concept was first introduced by European Commission on September 2001 after the terrorist attacks in the United States. The commission, together with the European Council and the European Parliament, designated 14 September 2001 as a day of mourning in member states and EU institutions. European citizens were asked to join in three minutes of silence. The Arab League observed three days of mourning for the death of King Fahd of Saudi Arabia on 4 August 2005. After these, many organizations observed day of international mourning for several times.