Admiral Mike Mullen, the chairman of the Joint Chiefs of Staff, said Monday that he was “surprised” by General James Amos' public comments against repeal of “Don't Ask, Don't Tell,” the 1993 law that bans gay and bisexual service members from serving openly, the AP reported.

Amos, the new commandant of the U.S. Marine Corps, told the Los Angeles Times that he was opposed to repeal of the law that has ended the military careers of more than 13,000 gay service members.

“There's a risk involved,” Amos, who assumed the helm two week ago from retiring General James Conway, said. “I'm trying to determine how to measure that risk. This is not a social thing. This is combat effectiveness.”

Amos is at odds with Secretary of Defense Robert Gates and President Barack Obama, both of whom have urged Congress to repeal the policy.

A Pentagon study on repeal, which includes a controversial survey of how troops and their families feel about the issue, is due on December 1.

Mullen said military leaders had committed to “look at the data and then make our recommendations privately.”

“I was surprised by what he said and surprised he said it publicly,” Mullen told reporters in Australia, where he is attending defense and diplomatic meetings.

Amos' predecessor, General James Conway, has also strongly objected to repeal of the law. “90 to 95 percent of the Marines” are against repeal, he told Fox News, citing impromptu surveys he had conducted by a “show of hands” at town hall meetings. Previously he had suggested that the Marines would consider separate quarters for gay service members if Congress repeals the policy, explaining that Marines don't want to bunk with gay service members because they are “very religious.”

Opponents of the policy are urging lawmakers to repeal the law during the upcoming lame-duck session of Congress before new members take their seats in January. A Republican majority in the House, and greater numbers in the Senate, will make repeal much more difficult in the next Congress. Arizona Senator John McCain has already pledged to filibuster any attempt at repealing the Clinton-era policy.