“The military’s “don’t ask, don’t tell” policy bars homosexuals who are publicly identified from serving in any of the services.“

While this is the way this matter it typically presented, it would be more accurate to say the following:

“The military’s “don’t ask, don’t tell” policy is the way the military complies with federal law that bars homosexuals who are publicly identified from serving in any of the services.”

The military didn’t decide to do this on their own, it is in execution of a law passed by Congress under their Constitutional authority to “raise and support armies.”