Washington ? President Barack Obama’s top military adviser said Sunday the Pentagon has enough challenges — including two wars — without rushing to overturn a decade-old policy that bans gays and lesbians from serving openly in the military and incites political and social factions on both sides.

Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, said he is working on an assessment of what — if any — impact overturning “don’t ask, don’t tell” policies would mean for the military and its culture. In the meantime, the Pentagon plans to follow the existing rules, which say gays and lesbians can serve in the military if they do not disclose their sexuality or engage in homosexual behavior.

During his presidential campaign, Obama pledged to overturn the Clinton-era policy and promised that gays and lesbians could serve openly in uniform. But he has made no specific move to do so since taking office in January. He has not set a deadline for repeal, has given the Pentagon no direct orders and has kept Capitol Hill guessing about when he might ask for a change in the law.