President Trump announced in a letter posted to social media on Saturday that he would place a 30 percent tariff on goods from the European Union, upending months of careful negotiations and further roiling what is one of the world’s most important economic relationships.

The president has published just 22 letters, many to minor trading partners like Brunei, Moldova and Sri Lanka.

For many countries, the reprieve from President Donald Trump’s eye-watering tariffs, which were implemented on April 2 and temporarily reduced to 10% a week later, is soon set to come to an end. The 90-day pause,