U.S. military officials said they are closely watching for reprisals for American air strikes in Iraq and Syria against an Iran-backed militia group, with the potential for a cycle of retaliatory actions that could inflame tensions between Washington and Tehran.
The U.S. military carried out the strikes on Sunday against the Kataib Hezbollah militia group in response to the killing of a U.S. civilian contractor in a rocket attack on an Iraqi military base.
On Monday, a top Iraq militia leader warned of a strong response against U.S. forces in Iraq following the air strikes that killed at least 25 people.
U.S. military officials, speaking to Reuters on the condition of anonymity, said they had little doubt the militia group would respond in some way which could lead to a new spike in tensions between the United States and longtime foe Iran.
"I think that they will retaliate," one military official said, referring to Kataib Hezbollah.
Another military official said that there was concern that the events over the past week could lead to a cycle of retaliation.
Iraqi security sources said that U.S. forces in Iraq's northerly Nineveh province were ramping up security overnight, with U.S.-led coalition jets circling the perimeter of its military bases in Mosul and Qayarah.