Washington ? It’s time to repeal the military’s “don’t ask, don’t tell” policy and allow gay troops to serve openly for the first time in history, the nation’s top defense officials declared Tuesday, with the chairman of the Joint Chiefs of Staff proclaiming that service members should not be forced to “lie about who they are.”

However, both Defense Secretary Robert Gates and Joint Chiefs Chairman Adm. Mike Mullen asked for a year to study the impact before Congress would lift the controversial policy.

Reversing the Pentagon’s 17-year-old policy toward gays “comes down to integrity,” for the military as an institution as well as the service members themselves, Mullen told a Senate hearing. Unpersuaded, several Republican senators said they would oppose any congressional effort to repeal the policy.

The Pentagon announced an 11-month review of how the ban could be lifted, as President Barack Obama has said he will work to do. But there is no deadline for ending the policy that dates to President Bill Clinton’s tenure and that gay rights advocates are pressing to overturn.

In the meantime, Gates announced plans to loosen enforcement rules for the policy, which says, in essence, that gays may serve so long as they keep their sexuality private.

Obama has called for repeal but has done little in his first year in office to advance that goal. If he succeeds, it would mark the biggest shake-up to military personnel policies since President Harry S. Truman’s 1948 executive order integrating the services.

Homosexuality has never been openly tolerated in the American military, and the 1993 policy was intended to be a compromise that let gay men and women serve so long as they stayed silent about their sexuality. Clinton had wanted to repeal the ban entirely, but the military and many in Congress argued that doing so would dangerously disrupt order.