US defence secretary Lloyd Austin told Congress on Tuesday that the Afghan army’s sudden collapse caught the Pentagon off-guard as he acknowledged miscalculations in America’s longest war including corruption and damaged morale in Afghan ranks.

“The fact that the Afghan army, we and our partners trained simply melted away, in many cases without firing a shot, took us all by surprise,” Austin told the Senate Armed Services Committee.

“It would be dishonest to claim otherwise.”

Austin was speaking at the start of two days of what are expected to be some of the most contentious hearings in memory over the chaotic end to the war in Afghanistan, which cost the lives of US troops and civilians and left the Taliban back in power.

The Senate and House committees overseeing the US military are holding hearings on Tuesday and Wednesday, respectively, and Republicans are hoping to zero in on what they see as mistakes that President Joe Biden’s administration made towards the end of the two-decade-old war.

The hearings follow similar questioning two weeks ago that saw US secretary of state Antony Blinken staunchly defending the administration, even as he faced calls for his resignation.

Biden has faced the biggest crisis of his presidency over the dramatic loss of the war in Afghanistan and America’s handling of its troubled withdrawal, raising questions about his judgment and foreign policy expertise.

Senator James Inhofe, the Senate Armed Services Committee’s top Republican, squarely blamed the Biden administration. Inhofe said Biden ignored the recommendations of his military leaders and left many Americans behind after the US withdrawal.

“We all witnessed the horror of the President’s own making,” Inhofe said.

Army General Mark Milley, chairman of the Joint Chiefs of Staff, testified that he did not anticipate the speed of the Taliban takeover. But he noted the military’s warnings since late 2020 that an accelerated withdrawal — without being tied to any conditions —could precipitate the collapse of the Afghan military and government.

“That was a year ago. My assessment remained consistent throughout,” Milley said.

Austin praised American personnel who helped airlift 124,000 Afghans out of the country, an operation that also cost the lives of 13 US troops and scores of Afghans.

“Was it perfect? Of course not,” Austin said, noting the desperate Afghans who died trying to climb the side of a U.S. military aircraft and the civilians killed in the last US drone strike of the war.