The U.S. military has begun drawing down troops as part of an agreement with the Taliban that could lead to all service members withdrawing from Afghanistan over the next 14 months.

“In accordance with the U.S.-Islamic Republic of Afghanistan Joint Declaration and the U.S.-Taliban Agreement, U.S. Forces Afghanistan has begun its conditions-based reduction of forces to 8,600 over 135 days,” said Army Col. William “Sonny” Leggett, the top U.S. military spokesman in Afghanistan.

“USFOR-A maintains all the military means and authorities to accomplish our objectives—including conducting counterterrorism operations against Al Qaeda and ISIS-K and providing support to the Afghan National Defense and Security Forces,” Leggett continued. “USFOR-A is on track to meet directed force levels while retaining the necessary capabilities.”

Defense Secretary Mark Esper revealed on March 5 that the implementing arrangements about exactly how U.S. troops will leave Afghanistan have not yet been released to the public.

Two classified annexes to the withdrawal agreement spell out which types of attacks the U.S military and Taliban are not allowed to carry out and how the United States will share information about where its troops are with the Taliban, the New York Times revealed on Sunday.