Bush said punishment would follow if a military investigation verified allegations the Marines killed 24 people, including women and children, in the town of Al-Hadithah in November.
"The Marines are run by an incredibly proud group of men and women who understand the history and tradition of the Marines," Bush said. "And they'll get to the bottom of this. And if there is wrongdoing, people will be held to account. And at the same time what you're seeing is the Marine Corps reminding our troops about what it means to be a Marine, what it means to uphold the honor of that corps."
Earlier, the top U.S. general in Iraq, Lieutenant General Peter Chiarelli, said that he had ordered that U.S. troops be given training in ethical and moral behavior.
Iraqi Prime Minister Nuri al-Maliki has called the alleged incident in Al-Hadithah a "terrible crime" and has asked the U.S. military to draw up stricter rules of engagement for its troops.
(compiled from agency reports)