ABC News' Elizabeth McLaughlin and Jake Lefferman report:

Rep. Adam Kinzinger issued a stark warning about recent events in Iraq today on "This Week" and called for the extremist group ISIS, which has seized large amounts of territory within the country, to be crushed.

"What we're watching in Iraq and Syria frankly is the worst case scenario for the Middle East," Kinzinger, R-Ill., told ABC's Martha Raddatz.

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"What we've begun doing is very good, but I think we have to get even bigger and realize that the crushing and pushing back of ISIS, not only in Iraq but also in Syria, is utmost priority," he said.

His comments follow a week of targeted airstrikes by the U.S. near the Mosul Dam, now under ISIS control, and aid operations by international forces to combat the persecution of the Yazidi religious minority.

Kinzinger, who served in the U.S. Air Force in Iraq and is currently a reserve in the National Guard, was positive about the U.S. response but said the Obama administration could do more to push back ISIS forces in Iraq and Syria.

"The president has got to stand up in front of the American people and say, 'Look, you may be war-weary, but in five or ten years we don't want to look back and say we missed all the signs,'" Kinzinger said.

Rep. Tulsi Gabbard, D-Hawaii, who served in the National Guard in Iraq, said the U.S. needs to clarify its mission.

"What is our mission?" she asked. "What are we trying to accomplish here?"

Gabbard agreed the United States could do more such as arming Kurdish forces with heavy weapons, while Kinzinger suggested that U.S. Special Forces embed with the Iraqi military.

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