ISLAMABAD (AP) — A temporary truce between the United States and the Taliban took effect on Friday, setting the stage for the two sides to sign a peace deal next week aimed at ending 18 years of war in Afghanistan and bringing U.S. troops home.

If successfully implemented, the weeklong “reduction in violence” agreement, which came into force at midnight Friday local time (1930 GMT, 2:30 p.m. EST), will be followed by the signing of the peace accord on Feb. 29, wrapping up America’s longest-running conflict and fulfilling one of President Donald Trump’s main campaign promises.

Friday’s announcement of an agreement on terms for a peace deal follows months of negotiations between the two sides that have broken down before. Yet both parties have signaled a desire to halt the fighting that began with the U.S. invasion after the September 11, 2001, attacks by Osama bin Laden’s Afghanistan-based al-Qaida network.

Should the truce stand, the U.S.-Taliban deal would be followed within 10 days by the start of all-Afghan peace talks that could result in the formation of a new government in Kabul, a pledge from the Taliban not to allow terrorist groups to operate in the country, and the phased withdrawal of U.S. and other foreign troops over 18 months.

The plan is a gamble for Trump, who retweeted several news accounts of the agreement. If it’s successful, he will be able to claim to have taken a first step toward meeting his 2016 campaign pledge to bring American troops home. But if it fails, Trump could be painted by his Democratic adversaries in an election year as being naïve and willing to sacrifice the security of U.S. soldiers and American interests for the sake of political expediency.

For the Taliban, the successful completion of the truce and Afghanistan peace talks would give the group a shot at international legitimacy, which it lacked at the time it ran the country and gave bin Laden and his associates safe haven.

The truce, to be monitored by American forces, will likely be fragile and U.S. officials have noted the possibility that “spoilers” uninterested in peace talks could disrupt it. Determining who is responsible for potential attacks during the seven days will therefore be critical.

Both sides were cautiously optimistic in announcing the agreement that had been previewed a week ago by a senior U.S. official at an international security conference in Munich, Germany. The announcement had been expected shortly thereafter but was delayed in part because of Monday’s release of the results of Afghanistan’s disputed September 2019 elections that showed President Ashraf Ghani winning by an extremely narrow margin.

U.S. Secretary of State Mike Pompeo said in a statement that the peace agreement, to be signed in Doha, Qatar, by U.S. special envoy for Afghanistan Zalmay Khalilzad and Taliban representatives, will eventually lead to a permanent cease-fire. The deal also envisions guarantees from the Taliban that Afghanistan will not be used to attack the U.S. or its allies.

“We are preparing for the signing to take place on February 29,” Pompeo said. “Intra-Afghan negotiations will start soon thereafter, and will build on this fundamental step to deliver a comprehensive and permanent ceasefire and the future political road map for Afghanistan.”