U.S. President Donald Trump on Sunday threatened to impose a 50% tariff on China, after a report emerged that Beijing was preparing to deliver a shipment of new air defense systems to Iran.

“I hear news reports about China giving [Iran] the shoulder missiles... what’s called the shoulder missile, anti-aircraft missile. I doubt they would do that... but if we catch them doing that, they get a 50% tariff, which is a staggering — that’s a staggering amount,” Trump said, in response to a question on whether a previous threat of tariffs on countries found supplying military equipment to Iran would also apply to China.

Trump’s comments, made in a televised phone call with Fox News, came as CNN, citing insiders, reported on the same day that U.S. intelligence assessments suggested an impending Chinese shipment of man-portable air defense systems (MANPADS) — a shoulder-operated, surface-to-air missile platform — to Iran.

In his interview with Fox News, however, Trump stopped short of confirming the credibility of the underlying coverage, saying that such reports ”[don’t] mean much to me, because they’re still fake.”

Speculation has mounted over China’s role in Iran’s war efforts.