An advocacy group is threatening to sue the Trump administration if it goes ahead with a ban on transgender people in the military, the Washington Examiner reports.

The group, OutServe-SLDN, is prepared to go to court following Trump's tweet announcing a ban on transgenders serving in the military.

"If the president pushes this, we will take him to court," said Matt Thorn, executive director of the OutServe-SLDN. The group provides legal services to lesbian, gay, bisexual, and transgender members of the military, according to the Examiner.

Trump tweeted on Wednesday:

After consultation with my Generals and military experts, please be advised that the United States Government will not accept or allow...... — Donald J. Trump (@realDonaldTrump) July 26, 2017

....Transgender individuals to serve in any capacity in the U.S. Military. Our military must be focused on decisive and overwhelming..... — Donald J. Trump (@realDonaldTrump) July 26, 2017

....victory and cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail. Thank you — Donald J. Trump (@realDonaldTrump) July 26, 2017

But Thorn does not believe Trump has the authority to institute a ban.

The American Civil Liberties Union also criticized Trump's decision in a tweet: