In a statement Tuesday, the union said the complaint centered on disparaging comments made by Trump on the platform, formerly known as Twitter, about striking workers. Trump suggested that employers could fire workers for going on strike.

The move escalates an ongoing feud between Trump and Musk as the former president tries to win over Midwestern swing-state voters who backed him in 2016 but defected in 2020. It also exposes both men to legal repercussions from the National Labor Relations Board.

"I look at what you do," Trump said to Musk in the interview. "You walk in and you just say, 'You wanna quit?' They go on strike, I won't mention the name of the company, but they go on strike, and you say 'That's OK, you're all gone. You're all gone. So every one of you is gone.'"

[Editor's note - from the NLRB's site: https://www.nlrb.gov/about-nlrb/rights-we-protect/the-law/employees/right-to-strike-and-picket]