President Donald Trump said in a Truth Social post on Monday that he will be imposing a 100% tariff “on any and all movies that are made outside of the United States.”

Trump did not specify when or how the tariff could be enacted.

If Trump follows through with his threat, it would mark the first time he’s essentially imposed a tariff on a service rather than a raw good.

The president initially threatened a 100% tariff on foreign-produced movies in May, arguing that other countries offer tax incentives that have drawn filmmakers abroad. In his post on Monday, he singled out California, saying the state “has been particularly hard hit!”

Hollywood was completely caught off guard when Trump first previewed the tariff in May. “On first blush, it’s shocking and would represent a virtually complete halt of production,” one industry insider told CNN at the time. “But in reality, he has no jurisdiction to do this, and it’s too complex to enforce.”

American actors and directors generally prefer to work close to home. But “the fact is, it’s cheaper for Hollywood studios to pay for everyone to get on planes, pay for hotels, because the cost of labour, lack of rebates and the ability to make things overseas is infinitely cheaper,” Jay Sures, vice chairman of United Talent Agency, told CNN in May.