Donald Trump on Sunday announced on his Truth Social platform a 100% tariff on all movies “produced in Foreign Lands”, saying the US film industry was dying a “very fast death” due to the incentives that other countries were offering to draw American film-makers.

In his post, he claimed to have authorised the commerce department and the US trade representative to immediately begin instituting such a tariff.

“This is a concerted effort by other Nations and, therefore, a National Security threat,” Trump said in the Truth Social post. “It is, in addition to everything else, messaging and propaganda!”

“WE WANT MOVIES MADE IN AMERICA, AGAIN!” Trump added.

Commerce secretary Howard Lutnick posting on X said: “We’re on it.” Neither Lutnick nor Trump provided any details on the implementation. It was not immediately clear whether the move would target production companies, foreign or American, producing films overseas.

Film and television production in Los Angeles has fallen by nearly 40% over the last decade, according to FilmLA, a non-profit that tracks the region’s production. At the same time, governments around the world have offered more generous tax credits and cash rebates to lure productions, and capture a greater share of the $248bn that Ampere Analysis predicts will be spent globally in 2025 to produce content.

Politicians in Australia and New Zealand said on Monday they would advocate for their respective film industries, after the president’s announcement.

Australia’s home affairs minister Tony Burke said he had spoken to the head of the government body Screen Australia about the proposed tariffs. “Nobody should be under any doubt that we will be standing up unequivocally for the rights of the Australian screen industry,” he said in a statement.

New Zealand prime minister Christopher Luxon told a news conference the government was awaiting further detail of the proposed tariffs. “We’ll have to see the detail of what actually ultimately emerges. But we’ll be obviously a great advocate, great champion of that sector in that industry,” he said.

The announcement from Trump comes after he triggered a trade war with China, and imposed global tariffs which have roiled markets and led to fears of a US recession. The film industry has already been feeling the effects of the tariffs, as China in April responded to the announcements by reducing the quota of American movies allowed into that country.

China is the world’s second largest film market after the US, although in recent years domestic offerings have outshone Hollywood imports.

Former senior commerce department official William Reinsch, a senior fellow with the Center for Strategic and International Studies, said retaliation against Trump’s foreign movies tariffs would be devastating.

“The retaliation will kill our industry. We have a lot more to lose than to gain,” he said, adding that it would be difficult to make a national security or national emergency case for movies.