WASHINGTON (AP) — The nation's top military leader says strikes against Islamic extremists in Syria will be persistent and sustainable as President Barack Obama expands the military campaign to combat the terrorist threat.

Army Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, told a Senate panel on Tuesday that the airstrikes will not resemble the "shock and awe" bombardment of the Iraq war that began in March 2003.

Dempsey said the Islamic State militant group is not organized. He said the strikes will degrade the group.

Joining Dempsey was Defense Secretary Chuck Hagel, who defended Obama's strategy. Hagel said the U.S. is at war with the extremists as it is with al-Qaida. He said the fight will not be easy or brief.

Anti-war protesters filled the front rows at the hearing.

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