President Donald Trump posted letters to the leaders of Mexico and the European Union, saying they had not done enough to head off the new tariffs.

President Donald Trump in recent days slapped tariffs as high as 50% on dozens of countries, restoring the type of aggressive trade policy that sent stocks plummeting a few months ago. The new round of levies prompted little more than a shrug on Wall Street.

While Mexico was spared from Trump's so-called "Liberation Day" tariff rollout on April 2, the 30% rate for the E.U. is 10 percentage points higher than what the president said he would apply to America's largest trading partner in April but lower than his mid-May threat of 50%.

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.

Donald Trump has proposed huge levies on Brazil, prompting an outspoken response from the CEO of Embraer, which builds vital regional airliners.

The European Union braced on Friday for a possible letter from U.S. President Donald Trump outlining planned duties on the United States' largest trade and investment partner after a broadening of his tariff war in recent days.

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