A look at major questions surrounding the decade-long Afghan war:
Why is the U.S. in Afghanistan?
The U.S. invaded Afghanistan in October 2001 because the Taliban were harboring al-Qaida chief Osama bin Laden, who masterminded the Sept. 11 attacks. After the Taliban regrouped in 2005 and 2006, President Barack Obama ramped up U.S. involvement in the war after taking office in 2009. He said the goal was to reverse Taliban gains and "disrupt, defeat and dismantle" al-Qaida and its extremist allies who were allied with the Taliban.
How many U.S. forces have been killed?
1,796 U.S. troops have been killed in Afghanistan according to an Associated Press count. More than 15,000 are believed to have been wounded especially as the pace of combat accelerated under the Obama administration.
How many forces are still there?
There are about 90,000 U.S. troops in Afghanistan. Obama has pledged to withdraw 23,000 troops by the end of this summer and most combat troops by the end of 2014 as NATO hands over security responsibility to the Afghans.
What is the status of the Afghan government?
The Afghan government is almost completely funded by foreign donors, primarily the U.S. government. President Hamid Karzai's administration is widely seen as a patronage network, and the government is rife with corruption, though he has said he is fighting graft. International advisers have also been working closely with many government ministries to institute reforms.
The central government has limited power outside of the capital. In the provinces, local commanders and regional strongmen tend to hold more sway than edicts from Kabul. In much of the insurgent-heavy south, Taliban commanders operate a shadow government that attempt to operate completely outside of the control of Kabul.
What is the goal?
Over the years, the U.S. focus has expanded from defeating al-Qaida, which has been largely pushed out of Afghanistan, to ensuring that the government is not threatened by Islamist extremists that could enable al-Qaida to return. That's why the war continues despite the killing of Osama bin Laden in Pakistan last May. The U.S. aims to build the capacity of the Afghan government and its security forces so that it can stand against the insurgent threat after most foreign forces withdraw in 2014. The goal is to prevent the country from descending into further chaos and once again becoming a sanctuary for terrorists who threaten the U.S.
The U.S. has also reached out to the Taliban with the hope of negotiating a peace settlement that would bring the group into the political system and persuade them to break off ties with al-Qaida.
Analysts have raised serious doubts about the prospects for success on both these fronts.