The US and Afghanistan have reached the "last chapter" in their effort to establish a sovereign Afghanistan that can provide for its own security, Leon Panetta, the US defence secretary, said.
Panetta made the comments while meeting visiting Afghan President Hamid Karzai at the Pentagon on Thursday.
He said 2013 would mark an important turning point in the war, with Afghan forces due to begin taking the lead role in providing security across the country while coalition troops would only offer support and training.
"We've come a long way towards a shared goal of establishing a nation that you and we can be proud of, one that never again becomes a safe haven for terrorism," Panetta said in remarks at the start of the meeting in his office.
"Our partnership, forged... through almost 11 years of shared sacrifice, is a key to our ability to achieve the final mission."
Karzai met later on Thursday Hillary Clinton, the secretary of state, at the state department and was due to be received by President Barack Obama on Friday.
Most details of the administration talks were expected to be announced only after Obama's meeting in a joint statement and press conference with the leaders, officials said.
Victoria Nuland, the spokesperson for the state department, said earlier that Clinton and Karzai would discuss the security transition, 2014 elections, economic issues and Afghan reconciliation issues, among other topics.
The Obama administration has been considering maintaining a residual force of between 3,000 and 9,000 troops in Afghanistan to conduct counter-terror operations while providing some training and assistance for Afghan troops.
But the administration said earlier this week it did not rule out the possibility of a complete withdrawal of all US troops from Afghanistan after 2014.
While Karzai has been critical of US troop activity in Afghanistan, it is unclear how Afghan troops would perform without US helicopters, medical facilities, intelligence and other military support activity, of which Afghanistan has very little.
Karzai, in remarks in Panetta's office, said he was confident that during his trip Afghanistan and the US would be able to "work out a modality for a bilateral security agreement to ensure the interests of Afghanistan and also the interests of the United States."
The US is insisting on immunity for any US troops that remain in Afghanistan. That unsettled question is expected to figure in this week's talks and may come up at the White House on Friday, when Karzai meets Obama.