The nation's top military officer said Sunday he has advised President Obama to move "in a measured way" in changing the "don't ask, don't tell" policy that bans gays from serving openly in the military.

Obama as a candidate pledged to end the ban. As president, he has not said when or how he will take steps to do so, drawing criticism from gay rights activists and others. The president has pointed out that Congress in 1993 made into law a policy begun by President Bill Clinton.

"It's very clear what President Obama's intent here is. He intends to see this law change," Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, said on CNN's "State of the Union."

"I've had conversations with him about that. What I've discussed in terms of the future is I think we need to move in a measured way," Mullen said.

Mullen said he has discussed with his staff what steps might be taken to implement a change in the policy.

"I haven't done any kind of extensive review. And what I feel most obligated about is to make sure I tell the president, you know, my -- give the president my best advice, should this law change, on the impact on our people and their families at these very challenging times," he said.

Defense Secretary Robert Gates said last week that he has lawyers studying ways the law might be selectively enforced as part of an effort to find "a more humane way" to apply the law until it is changed.