President Bush says he is troubled by initial news reports that some U.S. Marines killed unarmed Iraqi civilians last year in the town of Haditha.
Mr. Bush said Wednesday there will be punishment if laws were broken.
The New York Times reported Wednesday that a U.S. military investigator uncovered evidence that 24 Iraqi civilians killed in Haditha last year all had gunshot wounds.
Meanwhile, a senior U.S. military officer said the allegations that Marines killed Iraqi civilians -- whether true or not -- can have a negative impact on U.S. military operations there.
Brigadier General Carter Ham said U.S. and Iraqi forces rely heavily on the support of the Iraqi people. He said anything that diminishes that support is not helpful to what soldiers are trying to do.
The New York Times also reported that the military investigation of the incident in Haditha contradicts claims by Marines that the civilians were killed by a roadside bomb.
News reports say Marines opened fire in Haditha after a bomb rocked a military convoy and killed one member of their squad. The Marine Corps initially attributed 15 civilian deaths to the bombing and an ensuing gun battle with insurgents.
Iraqi Prime Minister Nouri al-Maliki has denounced the alleged killings and said he would launch his own investigation.