The United States plans to reduce its troop presence in Afghanistan to 9,800 this year and will conclude its military intervention in the country by the end of 2016, a senior official has said.
US President Barack Obama is to announce the plan later on Tuesday at 18:45 GMT from the White House, depending on the Afghan government agreeing to sign a joint security agreement.
While current Afghan President Hamid Karzai has declined to sign the agreement, US officials said they were confident that either of the candidates seeking to replace him would give his approval, the Associated Press news agency reported.
"We will only sustain a military presence after 2014 if the Afghan government signs the Bilateral Security Agreement," a senior administration official told reporters.
The plan calls for the US military to draw down from its current force of 32,000 to 9,800 by the end of this year. Those troops would be dispatched throughout Afghanistan and focus on security missions and training Afghan security forces. They would not be engaged in combat missions.
Over the course of next year, the number of troops would be cut in half and consolidated in the capital of Kabul and at Bagram Air Field, the main US base in Afghanistan.
By the end of 2016, the US presence would be cut to a normal embassy presence and will staff a security office in the capital, as has been done in Iraq, the official added.
The officials providing details of the announcement insisted on anonymity because they were not authorised to discuss the plan by name ahead of the president.
Ahead of his remarks, Obama was expected to speak with Karzai, who has had a tumultuous relationship with the White House. The two leaders did not see each other while Obama was in Afghanistan, but they did speak by phone as Air Force One was returning to Washington.
Obama has also discussed his plans with several European leaders, including German Chancellor Angela Merkel, British Prime Minister David Cameron and Italian Prime Minister Matteo Renzi.
At least 2,181 members of the US military have died during the nearly 13-year Afghan war and thousands more have been wounded.
The total NATO presence, including US troops, is expected to be around 12,000 at the start of next year.