A rash of American combat deaths in Afghanistan is putting a spotlight on a stalemated 17-year war that is testing President Donald Trump's commitment to pursuing peace with the Taliban.

Trump has acknowledged that his original instinct was to withdraw from Afghanistan, but last week he suggested he is willing to stick it out, asserting that the United States is in “very strong negotiations”, an apparent reference to US envoy Zalmay Khalilzad's efforts to get the Taliban to agree to peace talks.

On the other hand, Trump indicated he had little confidence the talks are going to succeed.

“Maybe they're not. Probably they're not,” he said.

The human cost of the conflict rarely makes headlines in the US, leaving Trump with political room to manoeuvre. But that might be changing.

In early November, Brent Taylor, the mayor of North Ogden, Utah, and a major in the Utah National Guard, was killed by an Afghan soldier in Kabul. Last Saturday, Sgt. Leandro Jasso, a 25-year-old Army Ranger from Leavenworth, Washington, was mortally wounded in southern Afghanistan. On Tuesday, US officials said they had determined that Jasso probably was accidentally shot by an Afghan soldier during battle with an Al Qaida fighter.

The US military headquarters in Kabul announced on Tuesday that three US service members were killed and three wounded by a roadside bomb in Ghazni province, south of Kabul, where the Taliban have been resurgent. It was the deadliest attack on US forces in Afghanistan this year.

The Taliban, who ruled Afghanistan before US forces invaded in October 2001, carry out near-daily attacks on Afghan army and police forces, and in August the insurgents overran parts of Ghazni, leading to days of intense fighting before they were driven out. Ghazni was the only one of Afghanistan's 34 provinces where parliamentary elections could not be held in October because of security worries. Voting there has been postponed for a year.

Stephen Biddle, a professor of international and public affairs at Columbia University who has closely tracked the war from its beginning, said little that has happened in Afghanistan in recent years has grabbed the American public's attention, including a death toll since 2001 that now exceeds 2,400.

“The war hasn't produced torch-lit marches on the Pentagon or for that matter any meaningful effect on any election campaign,” Biddle said. “What (the uptick in casualties) could do is change the mind of Donald Trump. At a minimum, he is erratic and clearly doesn't like the war.”

In a Washington Post interview on Tuesday, Trump called the latest deaths “very sad” and said he was keeping troops there only because “experts” told him it was necessary.

Trump's predecessor, Barack Obama, ended the US combat mission in Afghanistan in 2014 with the aim of compelling the Afghans to provide for their own defence. Trump came to the White House having called the war a waste, but in August 2017, he announced he was recommitting US forces to winning in Afghanistan while revealing that his first instinct had been to pull the plug. Over several months, the Pentagon sent an additional 3,500 troops and changed the way it advises Afghan forces. There are now about 15,000 US troops in the country.

Trump's strategy in Afghanistan is built on hope that the Taliban can be drawn into peace talks. That has not yet happened, but some US analysts say prospects are better than at any time in the war.

David Sedney, who has worked on Afghan issues as a diplomat and civilian policy official since the war began, said he believes the chances for successful peace talks with the Taliban are low but are better than at any other time in the long conflict.

Sedney said he heard encouraging words from Afghans supporters of the government as well as those who favour the Taliban during a visit to the county in late October and early November.

“There's a growing expectation that peace is possible,” Sedney said.

Further complicating the outlook is the presence in eastern Afghanistan of an affiliate of the militant Islamic State (IS) group. Both the Taliban and the IS affiliate want to overthrow the Afghan government.

Gen Joseph Dunford, chairman of the Joint Chiefs of Staff, said earlier this month that efforts to draw the Taliban into peace talks are being made “below the surface". But he indicated that progress is insufficient.

“We're a long way from where we could say that we're on the right path,” Dunford said at the Halifax International Security Forum, referring to effectively combining military, political and social pressure on the Taliban.

Noting that US officials as recently as a year ago called the war a stalemate, Dunford said “it hasn't changed much” since.