Trump Threatens 50% Tariffs on Countries Arming Iran—But Legal Authority Remains Unclear

President Trump escalated his tariff threats Wednesday, announcing he would impose immediate 50% duties on "any and all goods" from countries supplying military weapons to Iran—a move that appears to target Russia and China but lacks clear legal grounding.

"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," Trump wrote on Truth Social. "There will be no exclusions or exemptions!"

The announcement raises immediate questions about enforcement. Just weeks ago, the Supreme Court struck down Trump's use of the International Emergency Economic Powers Act (IEEPA)—his go-to tool for imposing customized tariffs without congressional approval. Trump has since scrambled to reimpose duties using alternative authorities, but those mechanisms are far more cumbersome and don't easily allow for the kind of targeted, country-specific rates he's threatening here.

It's unclear what legal authority Trump would invoke to fulfill Wednesday's promise. The alternative tariff laws he's been forced to use require lengthy administrative processes and don't grant the same sweeping discretion the IEEPA once did.

Russia and China have historically provided Iran with missiles, air defense systems, and military technology—though both have been relatively restrained in their support during the current U.S.-Israeli assault on Iranian targets. Beijing and Moscow now face the prospect of massive tariffs on all exports to the U.S., potentially worth hundreds of billions of dollars annually, if Trump can find a way to make good on the threat.

The tariff announcement came alongside a bizarre claim that the U.S. is working with Iran on "regime change"—a statement that contradicts decades of American foreign policy and raises questions about what exactly Trump believes is happening in Tehran.

"The United States will work closely with Iran, which we have determined has gone through what will be a very productive Regime Change!" Trump wrote, offering no evidence of any leadership transition in Iran.

He added that Iran would cease uranium enrichment and allow the U.S. to "dig up and remove all of the deeply buried (B-2 Bombers) Nuclear 'Dust'"—an apparent reference to Iran's underground nuclear facilities. "We are, and will be, talking Tariff and Sanctions relief with Iran," he said.

The statements follow Trump's decision to pull back from a threatened full-scale military assault on Iran just two hours before his own deadline for Tehran to reopen the Strait of Hormuz. Instead, the administration announced a two-week cease-fire, the terms of which remain murky.

Trump's tariff threats have become a defining feature of his second term, but the Supreme Court's recent ruling has significantly constrained his ability to act unilaterally. The IEEPA allowed presidents to declare economic emergencies and impose tariffs with minimal oversight—a power Trump used liberally during his first term and attempted to revive after returning to office.

Without that authority, Trump must rely on older, more restrictive trade laws that require formal investigations, public comment periods, and specific findings of harm to U.S. industries. Those processes can take months or years, making it difficult to impose the kind of immediate, punitive tariffs Trump announced Wednesday.

Whether Trump will follow through—or can follow through—remains to be seen. For now, Russia and China are left to guess whether this is another empty threat or the opening salvo in a trade war that could dwarf anything seen during Trump's first term.