By David Lawder and Susan Heavey
WASHINGTON, April 8 (Reuters) - U.S. President Donald Trump said on Wednesday that imports from countries supplying Iran with military weapons will face immediate 50% tariffs with no exemptions, threatening the new duties just hours after agreeing to a two-week ceasefire with Tehran.
After more than five weeks of air strikes against Iran's missile launchers, military installations and weapons industry, Trump returned to a favorite foreign policy pressure tool - tariffs - effectively warning China and Russia in a social media post against restocking Tehran's military inventories.
But the U.S. Supreme Court stripped the U.S. president of his fastest and broadest tariff authority, the International Emergency Economic Powers Act, in February when it ruled that his broadest global tariffs imposed under the 1977 law were illegal.
"A Country supplying Military Weapons to Iran will be immediately tariffed, on any and all goods sold to the United States of America, 50%, effective immediately, There will be no exclusions or exemptions! President DJT," Trump wrote on the Truth Social site, without naming any countries.
China and Russia have helped Iran build military capacity to counter U.S. and Israeli pressure, supplying missiles, air-defense systems and dual-use technologies intended to bolster deterrence.
That support appeared capped during the U.S.-Israeli attacks on Iran. Both Beijing and Moscow have denied supplying any weapons recently, although allegations against Russia have persisted.
Reuters reported in February, prior to the first U.S. and Israeli strikes on Iran, that Tehran was considering a purchase of supersonic anti-ship cruise missiles from China. Reuters also reported in March that China's top semiconductor maker, SMIC, has sent chipmaking tools to Iran's military, according to two senior Trump administration officials.
"This is a China-related threat, the way I read it. And China will read it that way," said Josh Lipsky, vice president and chair of international economics at the Atlantic Council.
Although drone and missile parts routinely flow from Chinese entities to Iran, evading U.S. sanctions, Lipsky said Trump was unlikely to follow through with new tariffs in the near term because that would derail his planned trip to Beijing to meet with Chinese President Xi Jinping.
On Tuesday, U.S. Trade Representative Jamieson Greer said Trump would seek to maintain the current stability in the U.S.-China relationship, to preserve U.S. access to Chinese-produced rare-earth minerals and magnets while maintaining prior tariff levels. Greer said Trump wanted to avoid a "massive confrontation" with Xi.
ALTERNATIVE TARIFF TOOLS
Of Trump's still available trade tools, an active "Section 301" unfair trade practices action against Chinese goods from his first term would be the most likely vehicle for adding new tariffs quickly, Lipsky said.
A more limited tool would be Section 232 of the Cold War-era Trade Expansion Act of 1962, aimed at protecting strategic domestic industries on national security grounds, but it would limit duties to specific sectors, lacking the broad economy-wide impact of the prior IEEPA-based tariffs.
Trump's tariffs on Chinese goods over nearly eight years already have cut U.S. imports from China sharply, from a peak of $538.5 billion in 2018 to $308.4 billion in 2025, with further declines recorded in January and February of 2026.
Russia has been another source of arms technology for Iran, but U.S. imports of Russian goods also have shriveled since the invasion of Ukraine in 2022 and the wave of financial sanctions imposed on Moscow as a result of that move.
U.S. imports from Russia, one of the only countries not subject to Trump's now-cancelled "reciprocal" tariffs, jumped 26.1% to $3.8 billion in 2025. These imports are dominated by palladium, which is used in automotive catalytic converters, fertilizers and their ingredients, and enriched uranium for nuclear reactors. The Commerce Department already is moving to impose punitive tariffs on Russian palladium after an anti-dumping investigation.
(Reporting by Susan Heavey and David Lawder in Washington; Editing by Sharon Singleton, Matthew Lewis and Paul Simao)
