US President Barack Obama announced Tuesday that 34,000 US troops will withdraw from Afghanistan in the next year and vowed the grueling, bloody US conflict there would end by late 2014.
"After a decade of grinding war, our brave men and women in uniform are coming home," Obama said in his State of the Union address, winning applause and a standing ovation from lawmakers.
The long-awaited move effectively halves the size of the current 66,000-strong US force in Afghanistan, as NATO troops prepare to hand over control for security operations to some 352,000 Afghan security forces.
"We can say with confidence that America will complete its mission in Afghanistan, and achieve our objective of defeating the core of Al-Qaeda," Obama said, praising the sacrifices made since the 2001 US-led invasion of Afghanistan toppled its Taliban leaders.
With Afghan forces moving to assume control of security starting this spring, US and NATO-led forces will no longer be in charge of leading combat operations.
"Tonight, I can announce that over the next year, another 34,000 American troops will come home from Afghanistan," Obama said. "This drawdown will continue. And by the end of next year, our war in Afghanistan will be over."
There were no immediate details of how quickly the drawdown would take place. But a senior Pentagon official told AFP earlier that it would be tied to the fighting season in Afghanistan, which runs into the fall.
"The commanders will have discretion on pace and focus will be (on) keeping as many forces in play until after the fighting season," the official said.
Outgoing Pentagon chief Leon Panetta said he welcomed Obama's announcement, adding it was based on the advice of former commander General John Allen.
"This plan to continue drawing down our forces in a phased approach over the coming year was recommended by General Allen based on a thorough assessment of the ISAF campaign plan moving forward," Panetta said in a statement.
The war effort is on a promising path "to achieve the goal of this campaign - to deny Al-Qaeda a safe haven to attack our homeland," said Panetta, who is due to retire within days pending the Senate's confirmation of his nominated successor, former senator Chuck Hagel.
The defense secretary's comments appeared aimed at countering criticism from some Republicans in Congress that Obama has allegedly ignored military advice and crafted withdrawal plans based on political considerations.
On Sunday, Allen officially handed command of ISAF to General Joseph Dunford, who is expected to be the last US commander in Afghanistan.
A senior US official said Obama had telephoned Afghan President Hamid Karzai, British Prime Minister David Cameron and German Chancellor Angela Merkel to inform them of his decision to pull out the 34,000 troops.
Debate is also taking place within the administration on the size of a residual force -- to train Afghan soldiers and to conduct counterterrorism missions -- that will remain behind after the formal withdrawal.
Last month, US officials suggested it was theoretically possible that Washington would leave no troops in the country, though some observers saw that move as a negotiating tactic with Karzai in town.
The senior official said Washington remained committed to a long-term strategic partnership with Afghanistan, and reiterated that talks on a bilateral security agreement were still taking place.
Afghanistan has committed to taking full responsibility for its own security after US forces leave. NATO says it will no longer lead combat operations in the next two years, but will provide support to Afghan soldiers.