President Donald Trump on Saturday threatened duties of 30% on products from Mexico and the European Union, two of America’s biggest trading partners, in an ongoing tariff campaign that’s upended global trade since he retook office in January.

President Donald Trump on Saturday announced he’s levying tariffs of 30% against the European Union and Mexico starting Aug. 1, a move that could cause massive upheaval between the United States and two of its biggest trade partners.

Leaders from both economies had been trying to negotiate more favorable terms, only to have those efforts blown up by form letters.