President Joe Biden and other top U.S. officials were stunned on Sunday by the pace of the Taliban’s nearly complete takeover of Afghanistan, as the planned withdrawal of American forces urgently became a mission to ensure a safe evacuation.

The speed of the Afghan government’s collapse and the ensuing chaos posed the most serious test of Biden as commander in chief, and he was the subject of withering criticism from Republicans who said that he had failed.

Biden campaigned as a seasoned expert in international relations and has spent months downplaying the prospect of an ascendant Taliban while arguing that Americans of all political persuasions have tired of a 20-year war, a conflict that demonstrated the limits of money and military might to force a Western-style democracy on society not ready or willing to embrace it.

By Sunday, though, leading figures in the administration acknowledged they were caught off guard with the utter speed of the collapse of Afghan security forces. The challenge of that effort became clear after reports of sporadic gunfire at the Kabul airport prompted Americans to shelter as they awaited flights to safety after the U.S. Embassy was completely evacuated.

“We’ve seen that that force has been unable to defend the country, and that has happened more quickly than we anticipated,” Secretary of State Antony Blinken told CNN, referring to the Afghan military.

The turmoil in Afghanistan resets the focus in an unwelcome way for a president who has largely focused on a domestic agenda that includes emerging from the pandemic, winning congressional approval for trillions of dollars in infrastructure spending, and protecting voting rights.

Biden remained at Camp David on Sunday, receiving regular briefings on Afghanistan and holding secure video conference calls with members of his national security team, according to senior White House officials. His administration released a single photo of the president alone in a conference room meeting virtually with the military, diplomatic, and intelligence experts. The next several days would be critical in determining whether the U.S. is able to regain some level of control over the situation.

The Pentagon and State Department said in a joint statement Sunday that “we are completing a series of steps to secure the Hamid Karzai International Airport to enable the safe departure of U.S. and allied personnel from Afghanistan via civilian and military flights.” Biden ordered another 1,000 troops into Kabul to secure the evacuation.