President Donald Trump openly challenged U.S. allies on Wednesday by increasing tariffs on all steel and aluminum imports to 25% as he vowed to take back wealth “stolen” by other countries, drawing quick retaliation from Europe and Canada. The Republican president's use of tariffs to extract concessions from other nations points toward a possibly destructive trade war and a stark change in America’s approach to global leadership. It also has destabilized the stock market and stoked anxiety about an economic downturn. “The United States of America is going to take back a lot of what was stolen from it by other countries and, frankly, by incompetent U.S. leadership,” Trump told reporters on Wednesday. “We’re going to take back our wealth, and we’re going to take back a lot of the companies that left.” Trump removed all exemptions from his 2018 tariffs on the metals, in addition to increasing the tariffs on aluminum from 10%. His moves, based off a February directive, are part of a broader effort to disrupt and transform global commerce. He has separate tariffs on Canada, Mexico and China, with plans to also tax imports from the European Union, Brazil and South Korea by charging “reciprocal” rates starting on April 2. The EU announced its own countermeasures on Wednesday. European Commission President Ursula von der Leyen said that as the United States was “applying tariffs worth 28 billion dollars, we are responding with countermeasures worth 26 billion euros,” or about $28 billion. Those measures, which cover not just steel and aluminum products but also textiles, home appliances and agricultural goods, are due to take effect on April 1.