President Trump’s ban on transgender military personnel went into effect on Friday, nearly two years after he first announced the plan via a series of tweets. In July 2017, Trump tweeted that “transgender individuals” would no longer be allowed “to serve in any capacity in the U.S. military.” The policy reverses a 2016 decision by former President Obama that transgender individuals could serve their country openly, having found that they have minimal financial impact on the military. Trump has claimed that transgender troops pose “tremendous medical costs,” a claim that has been debunked, as they account for less than 10 percent of what the military spends on erectile dysfunction medication.

Since Trump’s first announcement, the policy has been delayed by court challenges, public protest, as well as groundbreaking congressional testimony from transgender troops. The Department of Defense has defended the policy, and claims it does not discriminate against transgender individuals—only requiring them to serve under the gender they were assigned at birth. Activists argue that stipulation is discriminatory, forcing transgender troops to chose between medical treatment for gender dysphoria and keeping their jobs.