American Airlines Group Inc. removed a passenger who refused to wear a face covering and banned him from taking flights in the future, capping a week in which U.S. carriers vowed to step up enforcement of mask use.

Brandon Straka won’t be allowed to fly on American until face coverings are no longer required, the company said in an email Thursday. Straka, a conservative activist with about 400,000 followers on Twitter, posted a video Wednesday saying he had been kicked off his flight for not wearing a mask. He also accused American’s employees of intimidating him.

Straka’s ban validates a warning U.S. airlines made this week when they vowed increased vigilance in requiring mask use amid mounting concerns about new COVID-19 infections. United Airlines Holdings Inc. pledged to ban passengers flouting the rules, which exempt small children and people with medical conditions or disabilities that prevent them from wearing face coverings.