WASHINGTON -- The United States on Friday mounted strikes at targets used by Iran-backed militias in Iraq and Syria, President Joe Biden said, delivering on his vow to retaliate for last weekend's drone strike that killed three American soldiers in Jordan.

In a statement, Biden said that under his direction, U.S. military forces began the strikes at the facilities that the Islamic Revolutionary Guard Corps (IRGC) and affiliated militia use to attack U.S. forces.

"Our response began today. It will continue at times and places of our choosing," Biden said.

"The United States does not seek conflict in the Middle East or anywhere else in the world. But let all those who might seek to do us harm know this: If you harm an American, we will respond," he added.

The U.S. military conducted strikes on seven facilities, including more than 85 targets in Iraq and Syria in the initial barrage of strikes, Defense Secretary Lloyd Austin said in a separate statement.

"This is the start of our response. The president has directed additional actions to hold the IRGC and affiliated militias accountable for their attacks on U.S. and Coalition Forces," Austin said.

"The president and I will not tolerate attacks on American forces. We will take all necessary actions to defend the United States, our forces, and our interests," he added.

Earlier in the day, Biden attended a ceremony marking the repatriation of the three fallen soldiers at Dover Air Force Base in Delaware. Also present at the ceremony was Austin and Joint Chiefs of Staff Chairman Gen. Charles Brown.

The initiation of the strikes came amid concerns that the war between Israel and the Hamas militant group could escalate into a broader war amid continued attacks from Iran-backed militants. (Yonhap)