Watch Live: Top military officials Austin, Milley, McKenzie testify before Congress on Afghanistan

The nation's top military officials will publicly be facing tough questioning from Congress about the execution of the withdrawal from Afghanistan, in their first appearance before lawmakers since the U.S. left the country at the end of August.

Secretary of Defense Lloyd Austin, Chairman of the Joint Chiefs General Mark Milley, and the head of U.S. Central Command, General. Frank McKenzie,  will face tough questions are appearing Tuesday before the Senate Armed Service Committee.

President Biden announced in April he would order the withdrawal of all U.S. troops and end the 20-year war in Afghanistan by the anniversary of the 9/11 terror attacks, a date he later moved up to August 31. But that plan to move out not just the U.S. military, but also hundreds of Americans and thousands of vulnerable Afghans who had helped the U.S. during the war, was largely dependent on the belief that the Afghan government would remain in power throughout the withdrawal.