Within days of the terrorist attacks of September 11, 2001, the U.S. government blamed Al Qaeda, led by Osama bin Laden in Afghanistan, while the Taliban regime that had sheltered Al Qaeda and bin Laden since 1996 refused President George W. Bush’s demand to surrender him. On October 7, 2001, Operation Enduring Freedom began as U.S. and British aircraft attacked Taliban strongholds, while coalition forces relied heavily on anti-Taliban fighters such as the Northern Alliance, supported by arms, advice, and air strikes. Kabul fell on November 13, and Kandahar collapsed on December 6, but surviving Taliban and Al Qaeda leaders withdrew into rural Afghanistan and Pakistan, and although American commanders believed they came close to capturing bin Laden at Tora Bora in December, he escaped to Pakistan. With the Taliban removed from power and many Al Qaeda leaders in flight, the coalition shifted from major combat toward nation building, investing billions of dollars in infrastructure and supporting the creation of representative government. By 2005, Afghans had elected a parliament and President Hamid Karzai, but his administration was plagued by corruption and by failure to build strong independent Afghan police and military forces. The Taliban resurged in 2005, adopting tactics such as suicide bombings and roadside improvised explosive devices that caused heavy casualties among soldiers and civilians, while many Afghan civilians increasingly blamed the U.S. for failing to protect them. Pakistan publicly presented itself as a U.S. ally while continuing to allow insurgents to reside within its borders, leading the U.S. to order drone strikes there, but these did not stop the Taliban’s revival, and by 2007 and 2008 insurgent violence and anti-American sentiment were both growing. In spring 2009, President Barack Obama selected General Stanley McChrystal to reshape the war around a counterinsurgency strategy modeled on the Iraq surge, including thirty thousand additional troops and a greater emphasis on protecting civilians. The Afghanistan surge began in 2010 and achieved some success even though fighting continued. In 2011, Osama bin Laden was found in Abbottabad, Pakistan, and killed by American forces in a firefight on May 2, and on June 22 Obama announced a plan to withdraw all U.S. troops by 2014, although as of October 2011 more than fifty thousand U.S. troops remained in Afghanistan and violence with insurgents continued.