Political chaos reigned in Afghanistan Monday as dueling presidential swearing-in ceremonies took place in Kabul.

Incumbent Afghan President Ashraf Ghani took the oath of office for a second term while Chief Executive Abdullah Abdullah, citing fraud, proclaimed himself Afghanistan's president at a rival inauguration event.

Although Ghani and Abdullah both claimed to have won September's presidential elections, Ghani last month was officially proclaimed the victor. Unlike U.S. and NATO forces commander Gen. Scott Miller, who attended Ghani's swearing-in along with U.S. Charge d'Affaires Ross Wilson and U.S. special envoy Zalmay Khalilzad, Abdullah has refused to recognize that outcome.

Several loud explosions outside the presidential palace compound briefly disrupted Ghani's inaugural address.

"Everyone is safe, no one hurt, including President Ghani," tweeted presidential spokesman Sediq Sediqqi, adding, "He had no bulletproof vest today, mortars landed during his speech, but he didn't move an inch, he stood solid."

The unofficial Twitter feed of Israel's Mossad intelligence agency identified the attack's perpetrator as ISIS and posted photos of a rocket launcher in a van it said was subsequently destroyed by Afghan security forces.

The competing presidential inaugurations come the day before Afghanistan's elected leaders are due to sit down for intra-Afghan talks with Taliban insurgents, under the terms of a Feb. 29 peace agreement signed in Doha by U.S. special envoy Khalizad and Mullah Abdul Ghani Baradar, deputy leader of the Taliban.

"Afghanistan has quite the new political mess on its hands," tweeted Michael Kugelman, the Wilson Center's senior associate for South Asia. "Amb. Khalilzad has his work cut out for him, again, in Kabul in the coming days," Kugelman added. "That deal with the Taliban he so painstakingly worked out? It's at risk of being all for naught, thanks to the latest-and very serious-political crisis. And it has nothing to do with the Taliban."

The intra-Afghan talks are seen as crucial for implementing the permanent cease-fire called for in the Doha accord. They would mark the first formal meeting for a political settlement between the Taliban and Afghan rulers who were installed — but never recognized by the Taliban — after the Islamic fundamentalist group was toppled by invading U.S. forces in 2001.

The Taliban had agreed to and largely upheld a "reduction in violence" during the week preceding the signing of the peace accord. But its fighters have since been ordered to resume attacks on Afghan security forces while refraining, as had been agreed on in Doha, from targeting U.S. and NATO forces.

U.S. warplanes last week launched what were called defensive strikes against Taliban fighters attacking the Afghan military. On Sunday, Afghan authorities signaled they were unwilling to hold back much longer from resuming offensive operations against the Taliban.

"Afghan forces will remain in defense mode until the end of this week under the guidance of President Ashraf Ghani because of the peace agreement," the Reuters news agency quoted Afghan Defense Minister Asadullah Khalid as saying in a statement. "But if the Taliban do not stop their attacks by the end of the week, our troops will target the enemy everywhere."

The Doha accord calls for drawing down the approximately 13,000-strong U.S. force in Afghanistan to 8,600 over the next 135 days, with all of the remaining troops to leave by May 2021. No formal conditions were set forth in the agreement for the troop withdrawal, which would include coalition forces and departure from all military bases in Afghanistan.

On Monday, as the dual presidential oath-taking turmoil was unfolding in Kabul, an unidentified U.S. military official told the Associated Press the U.S. troop withdrawal has now begun. That comes a week after Defense Secretary Mark Esper said he had given the go-ahead to Gen. Miller to begin the drawdown.

Adding to uncertainty about when and even whether intra-Afghan peace talks will get underway has been Ghani's refusal to comply with a provision in the Doha agreement — which the Taliban did not permit the Afghan government to take part in — calling for the release of up to 5,000 imprisoned Taliban fighters and up to 1,000 Afghan security forces before March 10, the date set for starting those talks.

On Monday, Reuters reported that Ghani plans to issue a decree this week authorizing the release of at least 1,000 "old, aging" Taliban prisoners.

The move is seen as an attempt to get the Taliban, which controls roughly 40% of Afghan territory, to sit down with other Afghans and map out a political settlement to end decades of war.