- September 11, 2001: Al-Qaeda hijackers fly passenger planes into the World Trade Center and the Pentagon, killing nearly 3,000 people. Top Al-Qaeda leaders, including Osama bin Laden, are known to have safe havens in Afghanistan, which is ruled by the Taliban. - October 7, 2001: A US-led military campaign begins with air strikes against Afghanistan, followed by an invasion, to hunt down bin Laden and topple the Taliban. - December 2001: The Taliban regime is forced from power, and Hamid Karzai is appointed to head a new government. An International Security Assistance Force (ISAF), mandated by the United Nations, begins to deploy. - January 2002: The United States begins taking suspects captured in Afghanistan to its naval base in Guantanamo, Cuba. The policy quickly becomes a major human rights scandal. - March 2003: The United States takes on a second front by leading a massive invasion of Iraq. This reduces the resources that the United States and its main allies can devote to Afghanistan. - August 11, 2003: The North Atlantic Treaty Organisation (NATO) engages in its first-ever mission outside its traditional zone of Europe by formally taking charge of the ISAF force. - October 9, 2004: Afghanistan's first presidential election takes place with little bloodshed. Karzai is proclaimed the winner. - February 2007: The reach of Taliban guerilla activity is brought home when guerillas attack a US base as vice president Dick Cheney visits, killing 24 people. US President George W. Bush vows to further boost his country's forces. - November 2008: The Democrat candidate Barack Obama is elected to the US presidency, vowing to end the war in Iraq and focus on Afghanistan. - December 1, 2009: Obama orders a 30,000-troop "surge" into Afghanistan but says a withdrawal will begin in July 2011. The number of NATO-led forces rises to a peak of 150,000 in the summer of 2010. - November 20, 2010: NATO leaders endorse a plan to start handing security responsibilities to Afghan forces, with the aim of ceding full control by the end of 2014 - March 22, 2011: Western military leaders start handing over authority to local Afghan forces, a process due to be completed by 2014. - May 2: Osama bin Laden is killed by US special forces. The killing prompts some critics of the war to say that with bin Laden dead, it has lost its purpose. - June 22: Obama announces the departure of 33,000 US troops by the middle of 2012. - September 20: Burhanuddin Rabbani, a former president and would-be peacemaker, becomes the highest-ranking Afghan to be killed in an insurgent attack since the start of the conflict. - September 22: The US military's top officer accuses violent extremism to Afghanistan, in a scathing and unprecedented public condemnation.