Afghanistan’s rival leaders were each sworn in as president in separate ceremonies on Monday, throwing plans for negotiations with the Taliban into chaos and creating a dilemma for the United States as it figures out how to move its peace deal with the Taliban forward.

The US-Taliban deal signed just over a week ago was touted as Washington’s effort to end 18 years of war in Afghanistan and was seen by many Afghans as the best opportunity yet for bringing an end to relentless wars.

But President Ashraf Ghani, who was declared the winner of last September’s election, and his rival Abdullah Abdullah, who charged fraud in the vote along with the elections complaints commission, have refused to settle their differences.

The two ceremonies were held at the same time, Ghani’s in the presidential palace and Abdullah’s next door in the Sapedar Palace, both packed with each rival’s supporters.

Those commanders also participated in the brutal civil war of the 1990s, raising fears that the divisions among Afghan leaders could lead to violence.When Washington and the Taliban insurgents signed their accord on February 29, the next crucial step was that Afghans would sit down and negotiate a road map for their country’s future.

They are looking to hammer out such thorny issues as women’s rights, free speech and the fate of tens of thousands of armed men on both sides of the 18-year war. Those negotiations were set to be held Tuesday in Oslo.

But the dispute between the top two candidates in last year’s presidential election over who actually won means the Afghan government side appears unable to present a united front.The US has said its troop withdrawal from Afghanistan will be linked to the Taliban keeping their counter-terrorism promises, but not to the success of talks between the Taliban and the Afghan government.

Afghanistan’s election commission has declared incumbent President Ashraf Ghani as the winner of September’s vote.His former partner in a unity government, chief executive Abdullah, and the election complaints commission say the results are fraught with irregularities. As a result, both Ghani and Abdullah declared themselves winners.

The two candidates are also backed by warlords who have a stake in who becomes president, complicating negotiations to break the stalemate being conducted.