WASHINGTON (AP) — The Defense Department has approved a new policy that will largely bar transgender troops and military recruits from transitioning to another sex, and require most individuals to serve in their birth gender.

The memo outlining the new policy was obtained Tuesday by The Associated Press, and it comes after a lengthy and complicated legal battle. It falls short of the all-out transgender ban that was initially ordered by President Donald Trump. But it will likely force the military to eventually discharge transgender individuals who need hormone treatments or surgery and can’t or won’t serve in their birth gender.

The order says the military services must implement the new policy in 30 days, giving some individuals a short window of time to qualify for gender transition if needed. And it allows service secretaries to waive the policy on a case-by-case basis.

Under the new rules, currently serving transgender troops and anyone who has signed an enlistment contract by April 12 may continue with plans for hormone treatments and gender transition if they have been diagnosed with gender dysphoria.

But after April 12, no one with gender dysphoria who is taking hormones or has transitioned to another gender will be allowed to enlist. And any currently serving troops diagnosed with gender dysphoria after April 12 will have to serve in their birth gender and will be barred from taking hormones or getting transition surgery.

The memo lays out guidelines for discharging service members based on the new policy. It says a service member can be discharged based on a diagnosis of gender dysphoria if he or she is “unable or unwilling to adhere to all applicable standards, including the standards associated with his or her biological sex, or seeks transition to another gender.”

It adds that troops must be formally counseled and given a chance to change their decision before the discharge is finalized.