Donald Trump threatens 50 per cent tariffs for any country supplying weapons to Iran

"A Country supplying Military Weapons to Iran will be immediately tariffed, on any and all goods sold to the United States of America, 50 per cent, effective immediately. There will be no exclusions or exemptions!" Mr Trump wrote.

In a separate post, the president indicated his administration was engaged in discussions regarding tariff and sanctions relief with Tehran, describing recent developments as a "very productive regime change".

The tariff threat emerged just hours after Trump announced a two-week ceasefire agreement with Iran, struck following several weeks of American airstrikes against the country.

Under the terms of the deal, Tehran agreed to temporarily reopen the Strait of Hormuz, a vital maritime trade route whose closure had caused significant disruption.

The eleventh-hour truce was reached after Trump issued an extraordinary ultimatum threatening to destroy Iran's "whole civilisation" if no agreement was secured.

Negotiations were facilitated through conversations with Pakistani Prime Minister Shehbaz Sharif and Field Marshal Asim Munir.

Mr Trump announced the ceasefire on social media less than two hours before his self-imposed Tuesday evening deadline, hailing it as a "big day for World Peace!"

The agreement triggered a sharp decline in oil prices.

The warning is primarily directed at Russia and China, both of which have maintained military ties with Tehran.

Russia has reportedly been considering supplying suicide drones to Iran and has provided intelligence and satellite imagery to the regime, though Moscow has itself relied on Iranian military technology, including the low-cost Shahed drone, for its operations in Ukraine.

China has consistently denied selling weapons to Iran but has supplied dual-use items such as drones and spare parts that Tehran has weaponised for its armed forces.

According to Reuters last month, Iran was close to finalising a deal to purchase Chinese-manufactured ship-killer cruise missiles.

The tariff threat could complicate preparations for a long-anticipated summit between Trump and Chinese President Xi Jinping scheduled for Beijing next month.

The president's legal authority to enforce such tariffs remains uncertain following a Supreme Court ruling in February that removed his primary mechanism for imposing trade levies at will.

The court struck down the 1977 emergency law Mr Trump had previously used to apply tariffs on countries as a pressure tactic.

His remaining options are more constrained and require lengthier processes, including specific justifications and thorough investigations before implementation.

One potential avenue is Section 338 of the Tariff Act of 1930, which permits presidential tariffs of up to 50 per cent, though this provision is intended to address discriminatory foreign trade practices against American goods rather than weapons sales.

The White House did not respond to requests for comment regarding what legal basis the president intends to invoke.