Stocks in Asia were mostly down Tuesday, after U.S. President Donald Trump imposed 25% tariffs on all U.S. imports of steel and aluminum.

President Trump said he plans to impose 25% tariffs against all steel and aluminum imports into the U.S. on Monday.

Korea’s KOSPI index fell by 2.5% on Monday, as Trump’s tariff moves could threaten both South Korea’s export-heavy economy, as well as the supply chains of its major manufacturers. Electronics giants Samsung and LG, and automakers Kia and Hyundai, all have manufacturing facilities in Mexico.