<Li> U.S.--Afghan Strategic Agreement </Li> <P> The War in Afghanistan (or the U.S. War in Afghanistan) followed the 2001 United States invasion of Afghanistan . The U.S. was supported initially by Canada and the United Kingdom and later by a coalition of over 40 countries, including all NATO members . The war's public aims were to dismantle al - Qaeda and to deny it a safe base of operations in Afghanistan by removing the Taliban from power . The War in Afghanistan is the longest war in United States history . </P> <P> Following the September 11 attacks in 2001, U.S. President George W. Bush demanded that the Taliban hand over Osama bin Laden and expel al - Qaeda; bin Laden had already been wanted by the U.S. since 1998 . The Taliban declined to extradite him unless given evidence of his involvement in the September 11 attacks and also declined demands to extradite others on the same grounds . The U.S. dismissed the request for evidence as a delaying tactic, and on 7 October 2001 launched Operation Enduring Freedom with the United Kingdom . The two were later joined by other forces, including the Northern Alliance which had been fighting the Taliban in the ongoing civil war since 1996 . In December 2001, the United Nations Security Council established the International Security Assistance Force (ISAF), to assist the Afghan interim authorities with securing Kabul . At the Bonn Conference the same month, Hamid Karzai was selected to head the Afghan Interim Administration, which after a 2002 loya jirga (grand assembly) in Kabul became the Afghan Transitional Administration . In the popular elections of 2004, Karzai was elected president of the country, now named the Islamic Republic of Afghanistan . </P> <P> NATO became involved in ISAF in August 2003, and later that year assumed leadership of it . At this stage, ISAF included troops from 43 countries with NATO members providing the majority of the force . One portion of U.S. forces in Afghanistan operated under NATO command; the rest remained under direct U.S. command . </P>

What is the cause of the afghanistan war
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