© AP Photo/Gulnara Samoilova. Hijacked airliners are flown into the twin towers of the World Trade Center in New York and the Pentagon, outside Washington DC. A fourth plane crashes in Pennsylvania. In an address to the nation, President Bush describes the attacks as "deliberate and deadly terrorist acts." He says he has directed the US intelligence and law enforcement communities "to find those responsible and bring them to justice," adding that the US "will make no distinction between the terrorists who committed these acts and those who harbor them."

President Bush declares that the attacks were "acts of war."

The United Nations Security Council passes Resolution 1368, recognizing "the inherent right of individual and collective self-defence" and calling on all states to work together to bring the perpetrators of the attacks to justice.

The North Atlantic Council for the first time invokes Article 5 of NATO’s founding treaty, stating that an armed attack against any member state shall be considered as an attack against all.

Congress passes a resolution giving the President authorization for the use of force "against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons."

In an address to a joint session of Congress, President Bush says all the evidence suggests al-Qaeda was responsible for the attacks, and warns the Taliban regime that they must "hand over the terrorists, or they will share in their fate."

The Department of Justice issues an Interim Rule stating that non-citizens can be detained for 48 hours without charge, or in the event of an "emergency of other extraordinary circumstance" for "an additional reasonable period of time."

Chief Immigration Judge Michael Creppy sends a memo to immigration judges, advising them that deportation hearings for people suspected of involvement in terrorism should be unannounced and closed to the public.