The U.S. has started to withdraw troops from Afghanistan in compliance with its agreement with the Taliban, even as the peace process initiated by that deal faces its first delay and renewed violence across the country.

Negotiations between the Taliban and other Afghans, including government officials, were scheduled to start Tuesday, but will not happen yet. They have so far been bogged down by political fighting among Afghan officials over who will be part of the Afghan delegation amid a dispute over the results of last fall’s presidential election. But they’ve also been stuck over the deal’s call for releasing thousands of Taliban prisoners, with President Ashraf Ghani refusing to do so and the militant group saying it must happen first.

Ghani held an inauguration ceremony on Monday, nearly six months after the election that wasn’t called until late last month when Afghanistan’s election commission declared he won a very slim majority to stay in office. But that ceremony came under violent attack by the Islamic State, even as it was challenged across town by his rival and former chief executive Abdullah Abdullah, who held his own inauguration and claims to be the real winner.

Shortly after Ghani took the oath of office and while he was still addressing his inaugural crowd, they were shaken by the sound of explosions — rockets fired from a station wagon on the outskirts of Kabul landing near the presidential palace, its charred husk still smoldering and the launcher barely intact when security officials arrived.

ISIS later claimed responsibility for the attack, underscoring the enduring threat from the terror group’s branch in the region and its possible growth now that the Taliban has signed a peace deal with the U.S.

Abdullah, who alleges the election count was marred by fraud, held his own ceremony with supporters, but Ghani’s inauguration was boosted by international support, with the United Nations special envoy for Afghanistan Tadamichi Yamamoto, the head of U.S. Forces Afghanistan Gen. Austin Miller, and Ambassador Zalmay Khalilzad, the chief U.S. negotiator with the Taliban, all present.

Still, that political divide may derail the peace process before it really begins, with their rival claims threatening to divide Afghan leaders and institutions and possibly to burst into violence.

To prevent that, Secretary of State Mike Pompeo laid out a firm line, saying in a statement Monday, “We strongly oppose any action to establish a parallel government, and any use of force to resolve political differences.”

Khalilzad has also been in Kabul since last week, shuttling between different Afghan leaders and pressing them to form a negotiating team to meet the Taliban.

“We will continue to assist,” he tweeted late Monday, adding that Ghani and Abdullah both “made clear that they are open to negotiations to end the political crisis and that peace and reconciliation is the priority.”

During his inaugural address, Ghani said he will announce the members of the Afghan delegation on Tuesday, according to the Associated Press, although it’s unclear if Abdullah will try to announce his own as well or had signed onto Ghani’s.

Either way, those negotiations, scheduled to start Tuesday in Oslo, Norway, will not begin on time, in particular because Ghani’s government still has not released any Taliban fighters that it holds prisoner — although that could soon change, too.

The U.S.-Taliban agreement says that the U.S. will facilitate the release of up to 5,000 Taliban prisoners held by the Afghan government and up to 1,000 from the “other side” held by the Taliban, all of whom “will be released” by March 10. But a separate joint statement signed by the U.S. and Afghan governments on the same day says only both governments will discuss the “feasibility of releasing significant numbers of prisoners on both sides,” without committing to any number or time frame.

That discrepancy has left talks in limbo, with the Taliban demanding prisoners be released first while Ghani saying it must be part of the negotiations.

Despite that initial opposition, Ghani indicated some middle ground on Monday, saying he would issue a decree on Tuesday about Taliban prisoners, which Khalilzad and Pompeo both said they welcomed.

One piece of the agreement is now being implemented — the withdrawal of American troops.

According to the deal, the U.S. will drawn down its approximately 13,000 troops to 8,600 within 135 days and close its five major military bases — a process that started Monday, according to Col. Sonny Leggett, spokesperson for U.S. Forces in Afghanistan, or USFOR-A.

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

Gen. Miller and other senior U.S. officials have said that 8,600 troops are still sufficient for conducting U.S. operations, and the agreement allows the U.S. to pause and take stock after that initial withdrawal to see if the Taliban is keeping its commitments before withdrawing the remaining forces within 14 months.

That withdrawal is underway despite renewed attacks by the Taliban against security forces of the Afghan government, which the Taliban rejects as a U.S. puppet. Last week, there were dozens of attacks across the country, with U.S. forces even conducting airstrikes on Wednesday to disrupt a Taliban attack — the first time in weeks amid a push to reduce violence.

Last Thursday, Pompeo called the level of violence “unacceptable,” but said the Taliban’s leaders were trying to contain their fighters, adding that they were “working diligently to reduce violence from previous levels during similar time periods, and so we still have confidence the Taliban leadership is working to deliver on its commitments.”

While still demanding its fighters be released, the Taliban said Friday it was ready to begin negotiations: “Our negotiation team and agenda are ready and will go ahead as agreed.”