President Trump says transgender recruits are too expensive for the U.S. military, and that's why he's banning them from serving their country ... in any capacity.

Trump dropped the announcement Wednesday morning on Twitter, of course, saying transgender individuals are banned from serving because it "cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail."

It's not the first time he's gone after the transgender community. Back in February ... the Trump administration withdrew federal protection for transgender students.

The Prez championed himself as a supporter of the LGBT community ... saying he would fight for them while "Hillary brings in more people that will threaten your freedoms and beliefs."