Barack Obama and Hamid Karzai discuss Afghan endgame
President Barack Obama has welcomed his Afghan counterpart, Hamid Karzai, to the White House to discuss the future role of the US in Afghanistan.
US troop levels beyond 2014, prospects for Taliban peace talks and forthcoming Afghan elections are all on the agenda.
The meeting caps Mr Karzai's three-day trip to Washington that included talks with Defence Secretary Leon Panetta and Secretary of State Hillary Clinton.
Most of the 66,000 US troops in Afghanistan are due to leave in 2014.
US commanders have suggested leaving between 6,000 and 15,000 troops in Afghanistan to pursue insurgents and train Afghan security forces.
But White House officials have not excluded the possibility of withdrawing all troops by the 2014 deadline.Bilateral security agreement
The leaders are due to hold a joint press conference on Friday afternoon.
Obama administration officials said there would be no announcement about decisions on the next phase of troop withdrawals.
On Thursday, Mr Karzai met Mr Panetta and Mrs Clinton, both of whom are leaving their posts within the Obama administration.
At a news conference with the Afghan leader on Wednesday, Mr Panetta said: "After a long and difficult path, we finally are, I believe, at the last chapter of establishing an Afghanistan, a sovereign Afghanistan, that can govern and secure itself for the future."
It is hoped that the Nato coalition in Afghanistan, led by the US, will be able to hand over all combat missions to Afghan forces by the end of 2013.
Mr Panetta also said that progress had been made determining what kind of equipment the US would give to Afghan forces to keep their borders safe and stop a future Taliban insurgency.
Mr Karzai received a ceremonial welcome at the Pentagon. Later in the day he attended an official dinner at the state department.
His trip to Washington comes at a crucial time for relations between the two countries.
It follows a strained year between the US and Afghanistan, one that saw a series of attacks on US and Nato troops by members of the Afghan military and police, and a string of incidents involving US forces that enraged Afghans, including the burning of Korans.
But the Afghan leader's trip to Washington has been seen as a crucial step in negotiations over a bilateral security agreement that will determine the number and the function of US troops remaining in Afghanistan beyond 2014.
Mr Karzai has been reluctant to sign a long-term binding security agreement with the US amid fears it would undermine Afghan sovereignty.
Correspondents say he is unwilling to grant US soldiers immunity from prosecution and is unhappy that Afghans are still being held in US-run military prisons on Afghan soil.
US and Iraqi authorities reached a similar sticking point in negotiations over the drawdown of US troops from Iraq. Aside from a contingent guarding the embassy, all US soldiers left the country by December 2011.