Summary:Trump announces 25% tariff on countries trading with IranMeasure declared effective immediately, with no details providedChina, UAE, India and Turkey among Iran’s key partnersRaises risk of higher costs for Chinese goods entering USAdds fresh uncertainty to global trade and geopoliticsTrump unveiled a sweeping 25% tariff threat on countries trading with Iran, injecting new uncertainty into global trade and geopolitics.U.S. President Donald Trump on Monday announced a sweeping new trade measure targeting countries that do business with Iran, declaring that any such nation will face a 25% tariff on all trade with the United States, effective immediately.In a post on his Truth Social platform, Trump said the tariff would apply to “any Country doing business with the Islamic Republic of Iran,” adding that the order was “final and conclusive.” The announcement comes as Iran faces its third consecutive week of anti-government protests, raising the prospect that Washington is using trade policy to intensify economic pressure on Tehran indirectly by targeting its commercial partners.The White House declined to provide further details on how the tariff would be implemented, including how the administration defines “doing business” with Iran or whether exemptions, thresholds, or phased enforcement could apply. The lack of clarity has left markets and trade partners assessing the scope and enforceability of the move.Iran’s major trading partners include China, the United Arab Emirates, India, and Turkey. Among those, China is also one of the United States’ largest trading partners, raising the possibility that the new tariff could significantly raise the cost of Chinese imports into the U.S. if applied broadly.The announcement adds a new layer of uncertainty to global trade flows and comes at a time when markets are already sensitive to geopolitical risk and the potential use of tariffs as a policy tool. Trump has previously signalled a willingness to deploy trade measures aggressively, both for national security objectives and as leverage in broader diplomatic disputes.Without formal guidance from the administration, analysts said the immediate market impact may be muted, but warned that any follow-through or clarification could have material implications for global supply chains, U.S.–China trade relations, and risk sentiment more broadly. ----China is a big importer of oil from Iran. This article was written by Eamonn Sheridan at investinglive.com.