Britain is set to leave a contingent of around 100 troops in Afghanistan to help support the embassy and other diplomatic efforts in Kabul, it is understood.
They will be part of a small footprint of foreign forces, including around 650 American soldiers, that will stay on the ground longer term as the 20-year military mission ends.
Ben Wallace, the UK defence secretary, and his US counterpart, retired four-star general Lloyd Austin said both countries were on track to complete the withdrawal of all other troops by the end of August, even as the Taliban gains ground.
The vast majority of US-led military personnel has already left.
"We have conducted our retrograde safely and orderly," General Austin said in opening remarks as he hosted Mr Wallace at the Pentagon on Monday.
One of the most symbolic moments in the closing stages of America's longest war happened a few hours earlier when General Scott Miller, the US commander in Afghanistan for nearly the past three years, departed Kabul.
US Marine General Kenneth McKenzie, based out of Tampa in Florida, will be in charge of remaining US troops on the ground, taking that role out of the Afghanistan theatre.
"This transfer of authority is … only the next milestone in our drawdown process," Gen. Austin said.
Mr Wallace, on the first full day of a trip to the United States, said: "On the UK side we want to pay tribute to all the support US forces in Afghanistan have given us all and, like yourselves, we are on track to leave together towards the end of August."
After holding a closed-door session together at the Pentagon about Afghanistan as well as other issues including the threat posed by Russia and the challenge of China, the two men travelled to Arlington National Cemetery to lay a wreath and pay their respects to the fallen in past wars, including the Afghan campaign.