US Military Admits Afghan War Was 'Strategic Failure'Twenty years of American blood and treasure spent in Afghanistan was reduced Tuesday to about six hours of testimony in the United States Senate, with the nation's top military officer admitting that the war amounted to a "strategic failure" that in the end, perhaps, could never have been won. The hearing before the Senate Armed Services Committee with U.S. President Joe Biden's top military officials saw a staunch defense of the efforts and sacrifices of the U.S. troops in Afghanistan, with lawmakers both praising the decision to end the country's longest war and condemning its final days as a debacle. In between, it featured sobering assessments of what, if anything, could have been done differently. "It was a logistical success but a strategic failure," General Mark Milley, the chairman of the Joint Chiefs of Staff and the nation's top-ranking military officer, told lawmakers of America's final days in Kabul, which saw the evacuation of 124,000 people, including about 6,000 Americans. "Outcomes in a war like this, an outcome that is a strategic failure — the enemy is in charge in Kabul; there's no way else to describe that — that outcome is a cumulative effect of 20 years, not 20 days," Milley added. Pressed on whether Washington could have done anything differently to prevent the U.S.-backed government in Afghanistan from crumbling and stop the Taliban takeover, Milley was blunt. "If you kept advisers there, kept money following, etc., then we could probably have sustained them for a lengthy or indefinite period of time," he said of the Afghan government and the Afghan security forces. "If you would have had a different result at the end of the day, that's a different question," Milley added. "I think the end state probably would have been the same no matter when you did it." Testifying alongside Milley, General Kenneth "Frank" McKenzie, the commander of U.S. Central Command, said that in hindsight, the 2020 Doha agreement, which paved the way for the U.S. exit, "had a profound psychological effect" on the Afghan forces and may have hastened their collapse. "The Taliban were heartened by what they saw happen at Doha and what followed and our eventual decision to get out by a certain date," McKenzie said. "I think the Afghans were very weakened by that morally and spiritually." Republican anger Such somber assessments did little to mollify some lawmakers, with at least two demanding the resignations of Milley and Defense Secretary Lloyd Austin for the way the U.S. ultimately left. "Our exit from Afghanistan was a disaster," said Nebraska Republican Senator Deb Fischer. Another Republican, Senator Joni Ernst, called the U.S. evacuation from Afghanistan "haphazard." She pointed to the deaths of 13 U.S. troops and close to 170 Afghans from a suicide bombing at Hamid Karzai International Airport days before the last military plane took off. "The loss of our service members and abandonment of Americans and Afghan allies last month was an unforced, disgraceful humiliation that didn't have to happen," Ernst said. Some Democrats, however, praised Biden and his administration for finally ending the U.S. effort in Afghanistan. "It took guts, and it was the right thing to do, and it should have been done earlier," Virginia Senator Tim Kaine said. Others scolded their Republican colleagues. "Anyone who says the last few months were a failure but everything before that was great clearly hasn't been paying attention," said Massachusetts Democrat Elizabeth Warren. But most of the outrage was saved for the White House, with Republican lawmakers questioning the president's decision-making, and some accusing him of misleading the American public when he told ABC news last month that his top advisers did not recommend keeping about 2,500 troops in Afghanistan. "No, they didn't," Biden said at the time. "It was split." On Tuesday, both Milley and CENTCOM's McKenzie told lawmakers that in the early days of Biden's presidency, they advised keeping 2,500 to 3,500 troops in Afghanistan because the Taliban had not met their commitments under the 2020 Doha agreement. "My view is that 2,500 was an appropriate number to remain and that if we went below that number, in fact, we would probably witness a collapse of the Afghan government and the Afghan military," McKenzie said. WATCH: US reflects on Afghan war Cost of staying At the White House on Tuesday, press secretary Jen Psaki defended Biden and the decision to end the war in Afghanistan. "There was a range of viewpoints, as evidenced by their testimony today, that were presented to the president, that were presented to his national security team, as would be expected, as he asked for," she said. "It was also clear to him that that would not be a long-standing recommendation, that there would need to be an escalation, an increase in troop numbers," she said. "It would also mean war with the Taliban, and it would also mean the potential loss of casualties. The president was just not willing to make that decision." Milley also cautioned that staying in Afghanistan once the U.S.-backed government had collapsed could have been done, but at a cost. "On the first of September, we were going to go to war again with the Taliban. Of that there was no doubt," he told lawmakers, saying it would have required the U.S. to send in as many as another 25,000 troops. "We would have had to reseize Bagram (Airfield). We would have had to clear Kabul of 6,000 Taliban," Milley said. "That would have resulted in significant casualties on the U.S. side, and it would have placed American citizens that are still there at greater risk." Additionally, Milley and the other U.S. defense officials told lawmakers that even with troops and all but about 100 U.S. citizens out of Afghanistan and out of harm's way, dangers would remain from terror groups such as al-Qaida and the Islamic State Khorasan Province, also known as IS Khorasan or ISIS-K. "A reconstituted al-Qaida or ISIS with aspirations to attack the United States is a very real possibility," Milley warned lawmakers, adding that the exact nature of the threat might not be evident for months or years. "They're gathering their strength," CENTCOM's General McKenzie said of the threat from IS Khorasan, thought to have about 2,000 fighters now roaming Afghanistan. "We have yet to see how it's going to manifest itself," McKenzie said. "We know with certainty that they do aspire to attack us in our homeland." The U.S. first sent troops into Afghanistan to pursue al-Qaida, after the militant group used the country to plan the September 11, 2001, terror attacks on New York and the Pentagon. Milley and McKenzie said that despite the Taliban's commitments under the terms of the Doha agreement, the group had yet to sever its long-standing ties with al-Qaida. "I think al-Qaida is at war with the United States, still," Milley said. No going back For his part, Defense Secretary Lloyd Austin told lawmakers that the Pentagon remains focused on the threat but will use its over-the-horizon strike capabilities to target al-Qaida and IS Khorasan as needed. "We've not been tasked to construct any plans to go back," Austin said. Austin also defended the evacuation, telling lawmakers that it went as smoothly as possible, and that no other military in the world could have done any better. "It was the largest airlift conducted in U.S. history, and it was executed in just 17 days," he told committee members. "We planned to evacuate between 70,000 and 80,000 people. They evacuated more than 124,000." "Was it perfect? Of course not," Austin added, describing as "difficult" the first two days of the airlift, when huge crowds had rushed to the airport following the Taliban's unexpectedly swift takeover. "We moved so many people so quickly out of Kabul that we ran into capacity and screening problems at intermediate staging bases outside of Afghanistan," he said. But some lawmakers, such as the committee's top Republican, Senator Jim Inhofe, were unconvinced. "We all witnessed a horror of the president's own making," Inhofe said, accusing the Biden administration of failing to create a plan to counter the terror threats likely to emerge in Afghanistan with the Taliban in control. "The terrorist threat to American families is rising significantly," the senator said. "While our ability to deal with these threats has declined decidedly." Austin, Milley and McKenzie are all due to appear again Wednesday before the House Armed Services Committee.