The United States has increased its military presence in Iraq, ordering 300 more troops to the violence-ravaged nation, the Pentagon announced Monday. ISIS militants have "continued to pose a legitimate threat to Baghdad and its environs," a U.S. official told CNN.

"We have seen them reinforce themselves around Baghdad enough to convince us more troops was the prudent thing to do." The new troops, 200 of whom arrived Sunday and Monday, will provide security for the U.S. Embassy, the Baghdad airport and other facilities in Iraq, Pentagon spokesman Rear Adm. John Kirby said.

The deployment includes "a detachment of helicopters and unmanned aerial vehicles, which will bolster airfield and travel route security," Kirby said in a written statement.

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