The Iraqi government said at least three rockets hit the Baghdad International Airport on Friday, causing multiple casualties, the Associated Press reports. The rockets landed near the cargo hall, setting two cars on fire. A U.S. official said there are no reports of American casualties.

The missile attack comes after Defense Secretary Mark Esper said the U.S. military will be ready if Iran and its allies plan new attacks, like the one this week at the U.S. Embassy in Baghdad. More than 700 Army paratroopers are headed to Kuwait, as many as 5,000 more paratroopers and Marines are expected to be sent to the Persian Gulf in the coming days.

While speaking to reporters off camera, Esper said there are indications militias loyal to Iran are planning further attacks against Americans. "Do I think they may do something? Yes, and they will likely regret it," he said.

The embassy has been reinforced by more than 100 Marines and Joint Chiefs Chairman General Mark Milley said it is secure. "Anyone who attempts to overrun that would run into a buzz saw," Milley said.

In Baghdad, tensions are still incredibly high. American Apache helicopters are patrolling the skies over the embassy and the protesters have left, replaced by Iraqi elite forces guarding the compound.

But American troops and diplomats are also based at about 15 other locations in Iraq, some of which have come under rocket attack by Iranian-backed militias. Milley said last week's attack was the largest and deadliest yet.

"We know that the intent of this last attack was in fact to kill American soldiers," he said.

On Sunday the U.S. retaliated with airstrikes, which destroyed ammunition dumps but also led to the anti-American protest at the embassy. In the airstrikes on Sunday, U.S. planes deliberately avoided hitting buildings where Iranian advisers might have been located. They might not be so careful next time.

Ian Lee contributed to this report.