WASHINGTON (AP) — President Barack Obama's strategy to combat Islamic State extremists in Iraq and Syria is being scrutinized in Congress, where the expanded military campaign has broad support but faces skepticism after more than a decade of war.

Defense Secretary Chuck Hagel and Joint Chiefs Chairman Gen. Martin Dempsey are scheduled to testify Tuesday before the Senate Armed Services Committee. It's the first in a series of high-profile hearings.

Obama last week outlined his military plan to destroy the extremists, authorizing U.S. airstrikes inside Syria and stepping up attacks in Iraq.

The president said he had authority to order the airstrikes without congressional OK. Obamaasked lawmakers to authorize a program to train and arm vetted Syrian rebels battling the Islamic militants and forces loyal to Syrian President Bashar Assad (bah-SHAR' AH'-sahd).

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