In 2016, the ban on transgender people serving openly in the military was lifted. Now, U.S. President Donald Trump, with the Supreme Court’s approval, has reinstated that ban, citing concerns over transgender service members’ effectiveness in combat.

Kristin Beck, a transgender former Navy SEAL, is calling President Trump’s assertion baseless. “The idea transgender effects ‘Lethality and effectiveness’ which is total BULL SHIT,” she tweeted. In a separate tweet, she wrote that “18 other Nations ALLOW #Trans service members… zero issues!” adding, “I was a Navy SEAL for 20 years — I was pretty lethal.”

During her time in uniform, Beck served with SEAL Teams One and Five, eventually being recruited to Naval Special Development Group (DEVGRU), also known as SEAL Team Six. While in DEVGRU, she deployed to the Balkans, Iraq, Afghanistan, and numerous other undisclosed locations around the world. At one point, she was assigned to a Joint Task Force, which conducted very specialized taskings in Afghanistan. Her military awards include the Bronze Star with valor and the Purple Heart. She retired with the rank of senior chief petty officer (E-8).

“Let’s meet face to face and you tell me I’m not worthy. Transgender doesn’t matter. Do your service,” said Beck in an interview with Business Insider in 2017, when President Trump first tried to reimpose the ban.