The U.S. is not taking military action against the government of Bahrain like it is against the Libyan regime because the two countries have a long-held alliance, America's top military official said Sunday. 

Asked about the dichotomy on ABC's "This Week," Chairman of the Joint Chiefs of Staff Adm. Mike Mullen did not directly address Yemen, but said Bahrain has been a key U.S. ally in the Middle East.

"I think we have to be very careful to treat every country differently," he said. "Bahrain is in a much different situation than Libya."

Rulers in Bahrain and Yemen have used force against anti-government demonstrators, and some members of Congress have questioned why the U.S. government has not intervened to stop the violence there as it has in Libya.

The Obama administration has asked the governments of Yemen and Bahrain to exercise restraint and engage in dialogue with its opponents. Both nations' governments have relationships with the U.S. that are key for combating terrorism in the Middle East.

"We haven't had a relationship with Libya for a long, long time," Mullen said. "The Bahrainis and that country has been a critical ally for decades. So we're working very hard to support a peaceful resolution there, as tragic as it has been, and we certainly decry the violence which has occurred in Bahrain.

"I just think the approach there needs to be different."