WASHINGTON — Iran or its proxy forces may be planning further strikes on American interests in the Middle East, and the U.S. is prepared to take preemptive military action if it gets sufficient warning, Defense Secretary Mark Esper said Thursday.

“The game has changed,” Esper said, citing a series of violent attacks on U.S. personnel and facilities in Iraq in recent months by Iran-supported militia groups. “We're prepared to do what is necessary to defend our personnel and our interests and our partners in the region.”

On Tuesday, after a crowd of Iran-backed militiamen and their supporters stormed the U.S. Embassy compound in Baghdad, the Pentagon sent a Marine quick-reaction force to the embassy, and later it dispatched several hundred Army paratroopers from Fort Bragg, North Carolina. The paratroopers are in Kuwait as what Esper called “defensive support.”

Without providing details, Esper told reporters at the Pentagon that the U.S. has “indications” that more Iranian provocations may be in the offing. If that happens, he said, the U.S. will take action — preemptively, if it has enough advance warning.

Speaking alongside Esper, Gen. Mark Milley, chairman of the Joint Chiefs of Staff, said that if any group makes another attempt to overrun the embassy it will run into a “buzzsaw.”