President Barack Obama has announced thousands of US troops will remain in Afghanistan past 2016, retreating from a major campaign pledge as he admitted Afghan forces are not ready to stand alone.
Calling his decision to keep a 9800-strong US force in Afghanistan through much of next year "the right thing to do," the president on Thursday (local time) acknowledged "Afghan forces are still not as strong as they need to be."
"As commander in chief, I will not allow Afghanistan to be used as a safe haven for terrorists to attack our nation again," he said.
Obama's repeated promises to end America's "longest war," have again been thwarted by a dogged Taliban insurgency and Afghan forces slow to get to their feet.
Addressing battle-weary troops who may now be forced to return for another tour, Obama said they could "make a real difference" to stabilising a strategic partner.
"I do not send you into harm's way lightly," he told them.
"I do not support the idea of endless war, and I have repeatedly argued against marching into open-ended military conflicts that do not serve our core security interests."
Obama's decision - announced in a televised address from the Roosevelt Room of the White House - means he bequeaths to his successor a 14-year war that he inherited from George W Bush.
Coming to office in 2009, Obama had pledged to end a conflict that has now cost more than 2000 US lives and injured and maimed tens of thousands.
The war in Afghanistan was prompted by the Taliban refusal to surrender al-Qaeda leaders including Osama bin Laden after the 9/11 terror attacks.
NATO forces have been in the country since 2001, with the United States representing by far the largest contingent.
Under previous plans, the United States would have drawn down its troop numbers by the end of 2016 from about 10,000 currently, to about 1000.
But now, by late next year or early 2017 when Obama steps down and the 45th US president is sworn in, their numbers are expected to remain at about 5500.