President Trump made another major policy change and announced that the government will no longer allow transgender people to serve in the U.S. military. The announcement came via a series of tweets Wednesday. It isn’t clear if this means no new enlistments, or if the ban will extend to those currently enlisted.

In a series of tweets on Wednesday morning, he wrote:

“After consultation with my Generals and military experts, please be advised that the United States Government will not accept or allow … Transgender individuals to serve in any capacity in the U.S. Military. Our military must be focused on decisive and overwhelming … victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail. Thank you.”

The change, though announced through a series of tweets, is being enacted quickly.

Chief Pentagon spokesperson Dana White said in a statement, “Secretary Mattis today approved a recommendation by the services to defer accessing transgender applicants into the military until Jan. 1, 2018. The services will review their accession plans and provide input on the impact to the readiness and lethality of our forces.”

The ban on transgender service members was lifted back in June of 2016 by then-Secretary of Defense Ash Carter.

In 2016, Carter told NPR “that the Defense Department and the military need to avail ourselves of all talent possible in order to remain what we are now — the finest fighting force the world has ever known.”

Once the policy was enacted, the military could acknowledge that there were already numerous transgender service members.

NPR, citing Rand Corp. researchers, estimated “about 25,000 people out of approximately 825,000 reserve service members are transgender, with the upper end of their range of estimates of around 7,000 in the active component and 4,000 in the reserves.”

The estimates on the 2016 numbers seem high to many. Just how many took advantage of the shift in policy and enlisted in the last year is also unclear.

Trump is facing intense backlash for his decision. As NPR reminds its listeners, Trump promised his support for the LGBT community. Back in 2016, he tweeted “I will fight for you while Hillary brings in more people that will threaten your freedoms and beliefs.”