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.

President Donald Trump unleashed his latest tariff ultimatums, declaring a 30% rate for Mexico and the European Union, as his trade agenda continues to keep allies off balance and inject uncertainty into global financial markets.

"A 30% tariff on EU goods going to US would have a significant trade destruction effect. The threat to meet any EU tariff retaliation with a further and equal percentage point inc