The US Defence Secretary has issued an apology after it emerged that a group of US marines had posed with a flag that "adopted the SS insignia".
Leon Panetta's office expressed regret for the insensitivity displayed by the sniper team when it posed alongside a US flag and another bearing "a Nazi-related symbol".
The ten Marines, who were serving in Afghanistan at the time but are no longer with the unit, were given a warning but were not punished for their conduct.
Organisations including the Simon Wiesenthal Centre and the Washington-based Military Religious Freedom Foundation called on the US government to investigate the incident.
A spokesman for Mr Panetta said: "Racist and antisemitic symbols have absolutely no place alongside the men and women of America's armed forces."
Commandant of the Marine Corps General James F Amos said the Marines "unequivocally do not condone the use of any such symbols to represent our units".
He said that an investigation would take place into "the use of SS or other unauthorised symbols within the reconnaissance and sniper communities", as well as a review of the training and education of the unit.
Abraham Foxman, national director of the Anti-Defamation League, praised the Marines for condemning what had happened and working to "expunge the use of SS and other offensive or racist symbols in the military".
"The Marines and Defence Department have made clear that they are taking clear and immediate steps in response to this incident and to ensure that troops are appropriately sensitised in the future to all of the reasons why Nazi imagery and symbols have no place in the US armed services."