Financial markets, which have shown increasing insensitivity to tariff threats from the US, will face a test at the Monday open after President Donald Trump declared a 30% rate for the European Union and Mexico effective Aug.

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.

Mexico did not face a new tariff on April 2, the day of Trump's so-called "Liberation Day" tariff rollout. There remains a 25% tariff on non-USMCA-compliant goods from Canada and Mexico, as well as a 50% tariff on steel, aluminum and derivative products.

President Trump said he plans to impose blanket levies of 15% to 20% on most trading partners that haven't yet received suggested tariff rates. That would be higher than the 10% baseline currently in effect.

It shows that personal grudges rather than simple economics are a driving force in the U.S. leader’s use of tariffs.

Trump slapped a 50% tariff on Brazil, and Brazilian President Luiz Inacio Lula da Silva said his country would respond.

The president also decided to send out letters as a way to keep the pressure up.

President Donald Trump posted several more letters on social media on Wednesday, setting tariff rates ranging from 20% for products from the Philippines to 30% for products from Algeria, Iraq, Sri Lanka,