LONDON (AP) — Prime Minister Boris Johnson plans to set out details Thursday of Britain’s final military withdrawal from Afghanistan almost 20 years after the U.K. and other Western countries sent troops into the country.

Johnson told lawmakers Wednesday he felt “apprehensive” about the future of Afghanistan and that the situation was “fraught with risks.” The Taliban has been making rapid advances in many districts in the north as the United States completes its troop withdrawal. Most European troops have also quietly pulled out in recent weeks.

“We have to be absolutely realistic about the situation that we’re in, and what we have to hope is that the blood and treasure spent by this country over decades in protecting the people of Afghanistan has not been in vain and that the legacy of their efforts is protected,” Johnson said.

Britain’s Defense Ministry, citing security reasons, has declined so far to give details about its withdrawal beyond saying it would be “complete within a few months.” However, British media have reported that the last British troops left Afghanistan this week.

Defense Secretary Ben Wallace has said the U.K. had been put in a “very difficult position” to continue the mission once the U.S. announced its decision to leave.

A total of 454 British servicemembers died in Afghanistan during the U.K.’s deployment, a much higher death rate compared to the U.K. involvement in Iraq. Britain’s last combat troops left Afghanistan in October 2014, though about 700 remained in Afghanistan as part of a NATO mission to train Afghan forces.

The U.S. military announced Tuesday that 90% of American troops and equipment had already left the country, with the drawdown set to finish by late August. Last week, U.S. officials vacated the country’s biggest airfield, Bagram Air Base, the epicenter of the war to oust the Taliban and hunt down the al-Qaida perpetrators of the 9/11 terrorist attacks on America.