Top U.S. military leaders warned it’s possible al Qaeda could strengthen itself in Afghanistan and threaten the U.S. homeland in as little as a year, testifying that “over-the-horizon” operations will be difficult but not impossible.

Secretary of Defense Lloyd Austin, Joint Chiefs of Staff Chairman Gen. Mark Milley, and Gen. Kenneth “Frank” McKenzie, commander of U.S. Central Command, testified Tuesday before the Senate Armed Services Committee.