The U.S. will review its sanctions on the Taliban, with the goal of lifting them by late August, under a deal signed Saturday.

The agreement, signed in Doha, Qatar, seeks to end the longest war in U.S. history, which started weeks after the attacks on Sept. 11, 2001. 

The Taliban had ruled Afghanistan until the U.S.-led military invasion; the group had hosted Usama bin Ladin, leader of al-Qaida, who had overseen and led the attacks. About 2,400 U.S. forces and more than 43,000 Afghan civilians have died since the war began, according to figures from the U.S. Defense Department and the Costs of War Project at Brown University.

Under the deal, U.S. and allied forces would withdraw from Afghanistan over the course of 14 months, though the full pullout would depend on the Taliban meeting a variety of commitments against terrorism, including a renouncement of al-Qaida and taking active measures to prevent terrorists from using Afghan soil to plot future attacks against the U.S. or its allies.

“We will closely watch the Taliban’s compliance with their commitments and calibrate the pace of our withdrawal to their actions. This is how we will ensure that Afghanistan never again serves as a base for international terrorists,” Secretary of State Mike Pompeo said Saturday at the signing ceremony.

By Sunday, Afghan President Ashraf Ghani hadn’t pledged to free thousands of Taliban prisoners as laid out in the agreement, causing the deal’s first major snag. On Monday, the Taliban said they wouldn’t participate in intra-Afghan talks unless the prisoners are released.

A provision of the agreement also concerns sanctions. Removal of sanctions has long been a priority of the Taliban, according to a 2017 report by the Congressional Research Service.

The U.S. agreed, amid intra-Afghan peace negotiations scheduled to start March 10, to “initiate an administrative review” of its current sanctions and rewards list against Taliban members “with the goal of removing these sanctions by Aug. 27, 2020,” according to the deal’s text. The U.S. also agreed to start diplomatic talks with other members of the United Nations Security Council to remove Taliban members from U.N. sanctions lists within three months.

The Taliban and its then-leader, Mullah Mohammed Omar, were added by the U.S. in July 2002 to the annex of Executive Order 13224, the principal U.S. counterterrorism sanctions authority. (They had previously been sanctioned, in 1999, for providing safe harbor to bin Laden.) Since that time, the U.S. has sanctioned hundreds of individuals, entities and facilitators of the Taliban. Omar died in 2013 in a Pakistani hospital but the Afghan government didn’t announce it for more than two years.

Senior administration officials speaking to reporters during a briefing on Saturday said taking down the sanctions architecture is “part of the process of making peace” with the Taliban. The agreement’s language is “carefully constructed to be conditional,” however, an official said, hinging the delisting of the Taliban to its adherence to the agreement’s terms. 

“If the Taliban don’t do what we hope they’ll do, our requirements to take down that edifice are vitiated,” an official said.  

The U.S. had almost reached a deal in September 2019, but President Donald Trump called off the negotiations. By November, Trump made a surprise visit to Afghanistan, where he said the Taliban wanted a ceasefire, leading Taliban spokesmen to deny the claim. The talks resumed in December, were paused after a Taliban attack, but resumed again in January. 

Al-Qaida was concerned about the focus of Taliban leadership on the peace talks, according to a U.N. sanctions-monitoring report issued in mid-January. Representatives of al-Qaida “undertook shuttle diplomacy” seeking to persuade Taliban factions and field commanders not to support talks with the Afghan government and promising to increase financial support, the report said. Relations with the Taliban continue to be close and mutually beneficial, it said.

“If a peace agreement is reached, al-Qaida intends to develop a new narrative to justify continuing the armed conflict in Afghanistan,” the U.N. report said.