At the beginning of July, a spokesman for James Mattis said the secretary of defense had given his military chiefs another six months to study the impact of transgender people serving openly in the military.

That timeline has apparently been cut short. On July 26, President Donald Trump tweeted that transgender Americans would be barred completely from the nation’s armed forces.

“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,” President Donald Trump tweeted this morning from his personal Twitter account.

“Our military must be focused on decisive and overwhelming………victory,” Trump added, “and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail. Thank you”.

Trump’s decision came without any prior warning, and it appeared to catch the Department of Defense by surprise. Pentagon officials contacted by Task & Purpose appeared blindsided by their commander-in-chief’s morning Twitter storm.

Transgender troops had been permitted to serve openly in the military since last year, when then-Defense Secretary Ash Carter reversed a longstanding ban. He also gave the service chiefs a deadline of July 1, 2017, to come up with guidelines for accessions of new transgender military volunteers. When that deadline approached, the services asked Mattis for a delay in implementation so they could further study the issue. He gave them until Dec. 1.

But then the president tweeted.

What happens next is not entirely clear; the DoD did not immediately respond to a request for an on-record comment from Task & Purpose. According to a 2016 RAND report, there are an estimated 1,320–6,630 transgender troops currently serving in the military.

We will update you with more information as soon as it becomes available.