Trump threatened 50 percent tariffs on Iran’s arms suppliers hours after declaring a ceasefire, and experts say he may not have the power to do that

President Trump announced on Wednesday that any country supplying military weapons to Iran would face immediate 50 percent tariffs on all goods sold to the United States. The declaration, posted on Truth Social, specified that the levies would take effect immediately with no exclusions or exemptions. As reported by Politico, the announcement came just hours after Trump declared a two-week ceasefire with Iran, having posted on Truth Social overnight calling it a “big day for World Peace!”

The threat carries a significant legal complication. On February 20, 2026, the Supreme Court ruled in Learning Resources, Inc. v. Trump that the International Emergency Economic Powers Act, known as IEEPA, does not authorize the president to impose tariffs. That was the same law Trump had previously used to impose duties on Canada, Mexico, and China, citing national emergencies related to drug trafficking and trade deficits.

The ruling rested on a foundational constitutional principle: Article I, Section 8 grants Congress, not the executive branch, the exclusive power to lay and collect taxes, duties, and imposts. The government itself conceded during the case that the president has no inherent authority to impose tariffs during peacetime. With IEEPA no longer available as a legal basis, Trump’s options for making good on the new threat are substantially narrowed.

The legal path forward is murky, and a key diplomatic meeting may be at risk

The Court examined IEEPA’s list of authorized presidential actions, which includes the power to investigate, block, regulate, direct, compel, nullify, void, prevent, or prohibit imports and exports. Notably absent from that list, the Court observed, is any mention of tariffs or duties. The justices found that “regulate,” as ordinarily understood, does not encompass taxation, and could not identify another statute where the power to regulate included the power to tax. The Court also noted that in IEEPA’s half-century of existence, no prior president had ever invoked it to impose tariffs.

Trump’s remaining tariff tools require more specific justifications and thorough investigations before any duties can be put in place. One potential avenue is Section 338 of the Tariff Act of 1930, which allows tariffs of up to 50 percent, though it is designed to address foreign discriminatory trade practices against US goods. Experts say applying it to countries that supply weapons to Iran would be a significant legal stretch. His most legally defensible option, based on ongoing investigations into unfair trade practices, is not yet ready to deploy. However, Trump may attempt to rely on a prior investigation into China’s trade practices, conducted during his first term, to justify targeted tariffs on Beijing specifically.

That China angle is directly relevant to the new threat. Beijing is known to supply Iran with dual-use items including drones and spare parts. Reuters reported last month that Iran was close to finalizing a deal to purchase Chinese-produced cruise missiles capable of striking ships. The new tariff threat could complicate a long-anticipated summit between Trump and Chinese leader Xi Jinping, scheduled for next month in Beijing. The Chinese embassy in Washington had not responded to requests for comment at time of writing. Amid the broader regional instability, Iran struck Gulf oil facilities in the UAE, Kuwait, and Bahrain with missiles and drones on the same day the ceasefire was announced.

The White House had not commented on what specific legal authority Trump intends to use for the new threat. The tariff declaration arrived just hours after Trump announced the ceasefire, a sequence that drew attention to the rapid shift in posture. A House Democrat also filed articles of impeachment against Trump on the same day, citing the conflict in Iran and the president’s recent conduct as grounds for removal.