US President Donald Trump has announced a 25% tariff on imports from Japan and South Korea, escalating trade tensions over steel and transshipment issues. The move comes just before the expiration of a three-month tariff pause, affecting over 293,000 metric tons of steel shipped by the two countries in June. Trump has also hinted at similar letters being sent to 10 to 12 nations, extending the tariff campaign. Economic uncertainty and supply chain impacts loom large.