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.

Wall Street is pointing lower before the opening bell with new tariffs announced for Europe and Mexico and as the unofficial start of earnings season get under way this week. Futures for the S&P 500, Dow Jones Industrial Average and Nasdaq each retreated by about 0.3% early Monday.

The president has earned a reputation for bluffing on tariffs. But he has steadily and dramatically raised U.S. tariffs, transforming global trade.

If a 30 percent tariff on Mexico goes into affect on August 1, a wide variety of foods will be more expensive, experts warn.

Businesses typically pass tariff costs onto consumers through higher prices. Sometimes, that process is less subtle.