Trump's Tariff Threat on Iran-Arming Nations Divides White House on Legal Path

President Donald Trump threatened Wednesday to impose a 50 percent tariff "immediately" on any country supplying weapons to Iran, but his economic advisers are divided on which legal authority would support the move. White House National Economic Council Director Kevin Hassett argued the administration could use a 1977 emergency law, while U.S. Trade Representative Jamieson Greer said that same statute is better suited to trade prohibitions than tariffs.

Trump announced the tariff threat via social media, stating the duties would carry "no exclusions or exemptions" for countries providing military weapons to Iran. Hassett told Fox Business on Thursday that the International Emergency Economic Powers Act (IEEPA) is "exactly designed" for such action during a state of conflict. Hours later, Greer told Politico in Michigan that IEEPA could "prohibit" certain trade through embargo but is not well-suited for tariffs, though he said other tariff authorities remain under review.

A White House official declined to directly address the disagreement between the two advisers, stating only that "the President has numerous executive powers at his disposal to safeguard our national security, including IEEPA." The official, granted anonymity to discuss administration strategy, did not immediately respond to questions about Greer's contradictory position.

The legal dispute stems from a Supreme Court ruling on February 20 that rejected the administration's previous use of IEEPA to impose double-digit tariffs on dozens of countries. The Court found that IEEPA does not grant the president "expansive peacetime tariff power" without congressional approval, though justices did not directly address whether the law operates differently during active warfare.

Ed Gresser, a former U.S. Trade Representative economist now at the Progressive Policy Institute, said the wartime exception may create a narrow legal opening but cautioned it would be difficult to apply here. "I don't see how they can square that with a claim that, because we're in a state of conflict, the administration can use IEEPA to impose tariffs," Gresser said, noting the administration has not sought congressional authorization for military force against Iran over the past five weeks.

Context

The Trump administration has been rebuilding its tariff regime since the February Supreme Court decision. In response to that ruling, the administration already set a flat 10 percent tariff using Section 122 of the Trade Act of 1974, which permits duties up to 15 percent for 150 days to address balance-of-payments deficits. This earlier tariff action has already drawn legal challenges.

The IEEPA dispute reflects broader uncertainty about presidential tariff authority after the Court's decision. Peter Harrell, an economic adviser under former President Joe Biden, expressed skepticism about the administration's legal options. "I'm sure that if Trump actually tried to impose tariffs here, they'll be tied up in litigation for quite some time, and I am skeptical that the government would prevail," Harrell said. He suggested the administration would have clearer legal ground using sanctions rather than tariffs.

What's Next

The administration faces a choice between pursuing a legally vulnerable tariff approach or shifting to sanctions, which Harrell and others say have clearer statutory authority. Greer indicated the administration is actively reviewing options with Trump, suggesting a decision on the specific legal mechanism could come soon. Any tariff announcement will likely face immediate legal challenges given the February Supreme Court precedent, potentially delaying implementation well beyond Trump's stated "immediate" timeline.