01 Sep 2004 – Russia: The Beslan school hostage crisis, also known as the Beslan school siege or Beslan massacre, began in Beslan, North Ossetia-Alania, Russia. The siege finished three days later and resulted in the death of 380 people.
01 Sep 1970 – Jordon: Palestinian guerrillas expelled from Jordon; Black September takes its name from them.
03 Sep 1971 – Qatar: Qatar became an independent sovereign state
04 Sep 2006 – Philippines: Khadaffy Janjalani who was considered to be the nominal leader of the Abu Sayyaf terrorist group in the Philippines until his death in a gun battle with Filipino forces.
05/06 Sep 1972 – Germany: The terrorist group Black September kill members of the Israeli Olympic team in Munich
09 Sep 2004 – Indonesia: al-Qaeda attacks Australian Embassy in Jakarta killing 10 and seriously injuring 150.
11 Sep 2001 – United States: Four passenger planes hijacked; two crash into World Trade Center in New York City; one crashes into Pentagon; fourth crashes into a field in Shanksville, PA; nearly 3,000 killed; Osama Bin Ladin and al-Qa‘ida responsible
11 Sep 2012 – Libya: United States diplomatic facilities in Benghazi attacked; Ambassador Christopher Stevens and three other Americans killed.
13 Sep 2011 – Afghanistan: US Embassy and NATO headquarters in Kabul hit in simultaneous attacks with rocket-propelled grenades and small-arms fire; Taliban claim responsibility
Dates are taken from the NCTC terrorist calendar and 361 Security Significant dates.