Two of America's top military leaders will be defending President Barack Obama's handling of the tinderbox of violence and struggle in the Middle East.

Defense Secretary Ash Carter and Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, are to appear Wednesday before the House Armed Services Committee.

Rep. Mac Thornberry, the panel's chairman, said this is a perilous time in the Middle East and that U.S. policy and strategy are inadequate.

Carter and Dempsey will almost certainly be quizzed about U.S. strategy to quell the advance of Islamic State militants.

The White House last week announced the U.S. would send up to 450 troops to a new base in western Iraq, mainly to advise the Iraqis on planning and execution of a counteroffensive against IS.