The nation's top military leaders will face lawmakers on Capitol Hill on Tuesday in a hearing expected to touch on some of the most contentious national security challenges facing the country.

Joint Chiefs of Staff Chairman Mark Milley, Defense Secretary Lloyd Austin and U.S. Central Command Gen. Kenneth McKenzie will testify before the Senate Armed Services Committee on Tuesday and House Armed Services Committee on Wednesday.

The trio is expected to be grilled on their handling of the U.S. withdrawal from Afghanistan, competition with rivals like China, and, in Milley's case, reports that he may have circumvented his chain of command in sending reassurances to his Chinese counterpart.

Republican and Democratic lawmakers expressed frustration and outrage at the collapse of Afghanistan to the Taliban and later botched U.S. efforts at counterterrorism in the country.

GOP lawmakers are also likely to echo recent critiques that the top brass should be fired for their overall performance. President Joe Biden says he remains confident in his national security team, while most Democratic critics have stopped short of calling for the leaders to be kicked from office.