The attack against U.S. forces is the first since early February when Iranian-backed groups in Iraq stopped their attacks against U.S. troops.

The attack comes one day after Iraqi Prime Minister Mohammed Shia al-Sudani returned from a visit to the United States and met with U.S. President Joe Biden at the White House.

Two security sources and a senior army officer said a rocket launcher fixed on the back of a small truck had been parked in Zummar, a border town with Syria.

The military official said the truck caught fire with an explosion from unfired rockets at the same time as warplanes were in the sky.

We cant confirm that the truck was bombed by U.S. warplanes unless we investigate it, said a military official on condition of anonymity because of the sensitivity of the incident.

Iraqi security forces were deployed in the area and launched a hunt for the perpetrators who fled the area using another vehicle, said a security official who is based in the town of Zummar.

The Iraqi Security Medica Cell, an official body responsible for disseminating security information, said in a statement that Iraqi forces had launched a wide-ranging search and inspection operation targeting the perpetrators near the Syrian border, pledging to bring them to justice.

An army officer said the truck was seized for further investigation. An initial investigation shows that it was destroyed by an air strike.

We are communicating with the coalition forces in Iraq to share information on this attack, the officer added.

The attacks came one day after a huge blast at a military base in Iraq early on Saturday killed a member of an Iraqi security force that includes Iran-backed groups. The force commander said it was an attack while the army said it was investigating and there were no warplanes in the sky at the time.