On Friday, March 23, President Trump issued a memorandum adopting recommendations from Defense Secretary James Mattis stating, among other things, that “transgender persons with a history or diagnosis of gender dysphoria — individuals who the policies state may require substantial medical treatment, including medications and surgery — are disqualified from military service except under certain limited circumstances.”
The new memorandum expressly revokes the August 25, 2017 memorandum of the same title and provides that “The Secretary of Defense, and the Secretary of Homeland Security, with respect to the U.S. Coast Guard, may exercise their authority to implement any appropriate policies concerning military service by transgender individuals.”
Memorandum — March 23, 2018

Trump Approves New Limits on Transgender Troops in the Military — New York Times