Military Service by Transgender Individuals: Memorandum for the Secretary of Defense [and] the Secretary of Homeland Security, March 23, 2018 [open pdf - 172KB]
"Pursuant to my memorandum of August 25, 2017, 'Military Service by Transgender Individuals,' the Secretary of Defense, in consultation with the Secretary of Homeland Security, submitted to me a memorandum and report concerning military service by transgender individuals. These documents set forth the policies on this issue that the Secretary of Defense, in the exercise of his independent judgment, has concluded should be adopted by the Department of Defense. The Secretary of Homeland Security concurs with these policies with respect to the U.S. Coast Guard. Among other things, the policies set forth by the Secretary of Defense state 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."
Federal Register: http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR
Federal Register (March 28, 2018), vol. 83 no. 60, p. 13367