Elon Musk was asked on Twitter what he thinks about workers’ associations. To this, the entrepreneur replied that nothing stops Tesla employees from joining trade unions, they could do it even tomorrow if they wanted. However, they have no reason to agree to pay union dues and give up stock options.

In addition to deleting the tweet, Tesla will have to post an “illegal tweet” notice in its factories across the country.

It is not the first time that Elon Musk’s Twitter has been the subject of controversy. A Tesla investor recently filed a lawsuit against the entrepreneur and the company’s board of directors, over the fact that Musk’s “messy” tweets are exposing Tesla to billions of dollars in risks.