Defense Secretary Lloyd Austin told lawmakers at a House Armed Services Committee hearing he wouldn’t absolutely rule out sending troops back into Afghanistan, and added, "If we do, the military will provide good credible options to be able to do that and to be effective."

While maintaining that he wouldn’t talk about his recommendation to President Biden on leaving a residual force, Austin said he "did not support staying in Afghanistan forever" and that keeping a presence there would have required more troops for force protection if the Taliban started attacking the U.S. military as it had promised to do.

"Let me be clear that I support the president's decision to end the war in Afghanistan. I did not support staying in Afghanistan forever. And let me also say we've talked about the process that we used to provide input to the president," Austin said.

"I will always keep my recommendations to the president confidential but I would say that in my view there is no, was no risk-free status quo option. I think that the Taliban had been clear that if we stayed there longer, they were going to recommence attacks on our forces," Austin added.

"I think while it's conceivable that you could stay there, my view is that you would have had to deploy more forces in order to protect ourselves and accomplish any missions we would have been assigned. It's also my view, Mister Chairman, the best way to end this war was through a negotiated settlement and sadly that did not happen."

Rep. Michael Turner, R-Ohio, raising the August U.S. drone strike in Kabul that killed 10 Afghan civilians, including seven children, took direct issue with the U.S. military’s ability to conduct "over the horizon" drone strike capabilities in Afghanistan.

"What we know from your prior statements is that you did not know who it was, who was in the car, whose house it was," Turner said. "This greatly concerns me as we look to the over horizon claims that the administration has of its ability for counterterrorism."

Gen. Frank McKenzie, the commander of U.S. Central Command, told House lawmakers he took "full responsibility" for the strike.

"That strike was a mistake and I take full responsibility for that strike. I was under no pressure from any quarter to conduct the strike," McKenzie said.

"While in many cases we were right with our intelligence and forestalled ISIS- K attacks, in this case we were wrong, tragically wrong," he added.

"Over-the-horizon" capabilities are a cornerstone of the U.S. military’s counterterrorism strategy in Afghanistan. The top Pentagon commanders said the U.S. will continue to investigate the intelligence that led to the August strike and will be transparent with their findings.

Echoing Secretary of Defense Lloyd Austin, Gen. Mark Milley, chairman of the Joint Chiefs of Staff, said in his opening testimony that lawmakers can debate the decisions surrounding the Afghanistan withdrawal but that the courage of U.S. service members is not up for debate.

"Over the course of four presidents, 12 secretaries of defense, seven chairmen, 10 CENTCOM commanders, 20 commanders in Afghanistan, hundreds of congressional delegation visits, and 20 years of congressional oversight, there are many lessons to be learned," Milley said.

"One lesson we can never forget: every soldier, sailor, airman and Marine who served there for 20 years, protected our country against attack by terrorists, and for that we all should be forever grateful, and they should be forever proud," he said. 

Milley again took the chance to push back on recent characterizations of phone calls to China's top military official in the final days of former President Donald Trump’s presidency.

"At no time was I attempting to change or influence the process, usurp authority, or insert myself into the chain of command. But I am expected to give my advice and ensure that the president was fully informed on military affairs," he said.

Secretary of Defense Lloyd Austin, facing a House panel on Wednesday, repeated his opening testimony given to Senate lawmakers at Wednesday's hearing, in which Gen. Mark Milley, chairman of the Joint Chiefs of Staff, and Gen. Kenneth McKenzie, commander of U.S. Central Command, appeared to contradict Biden by saying they recommended keeping a residual force of 2,500 troops behind in Afghanistan.

Austin again defended leaving Bagram Airfield, saying it would have required at least 5,000 troops and would have "contributed little" to the mission of protecting the embassy in Kabul, which ultimately fell to Taliban control. 

"Staying in Baghram even for counterterrorism purposes meant staying at war in Afghanistan, something that the president made clear that he would not do," Austin said.

He again walked through some "uncomfortable truths" about the two-decade U.S. military mission in Afghanistan, of which he is a veteran.

"We helped build a state, but we could not forge a nation. The fact that the Afghan army that we and our partners trained simply melted away, in many cases without firing a shot, took us all by surprise and it would be dishonest to claim otherwise," he said.