Afghanistan, for much of the latter half of the 20th century, was wracked by civil war. In the 1980s Soviet troops intervened to install new rule, while the US backed Mujahedin rebels: the country became a Cold War battleground.
When Soviet troops withdrew at the beginning of the 1990s, the Mujahedin took power but were destabilized by factional rivalry, allowing hard-line Taliban to seize control of the capital and around two thirds of the country. The Taliban introduced strict Islamic law, and were suspected of providing harbour to al-Qaeda and its militant leader Osama bin Laden.
By the end of the century, the United Nations had imposed sanctions on the Taliban to force them to hand over Osama bin Laden for trail, as he was accused of bombing US embassies in Africa. In October 2001, the USA and Britain launched air strikes on Afghanistan after the Taliban had again refused to hand over Osama bin Laden, now held responsible for the September 11 attacks on the World Trade Centre in New York. On the ground the allies lent support to the anti-Taliban Northern Alliance, a multi-ethnic opposition group. By November the Taliban had fallen, but UN-sanctioned allied forces continued their military campaign to oust pockets of al-Qaeda and Taliban forces.