The incident, which was captured on video and posted online on Tuesday night, united the American and Afghan governments in condemnation yesterday, with Mr. Panetta promising a full investigation and swift justice for those responsible.

"I find the behavior depicted in the video utterly deplorable," Mr. Panetta said. "This conduct is entirely inappropriate for members of the United States military and does not reflect the standards or values our armed forces are sworn to uphold. Those found to have engaged in such conduct will be held accountable to the fullest extent."

US Secretary of State Hillary Clinton also expressed "total dismay" at the video, which appeared on YouTube, and said it was "absolutely inconsistent with the standards of behavior that the vast majority of Marines hold themselves to."