The Trump Administration withdrew from a longstanding trade agreement with Mexico governing the import of tomatoes and will push forward with a new tariff of just over 17%, the Commerce Department announced Monday.

The US is imposing a 17% tariff on most tomatoes imported from Mexico with immediate effect, the government said. The duty came into force after the US withdrew from a long-standing agreement with its southern neighbour, arguing that the deal "had failed to protect US tomato growers from unfairly priced Mexican imports".

President Trump is pushing through with his tariff agenda, unveiling a new batch of letters to country leaders outlining tariffs on goods imported from their countries beginning in August. Trump on Thursday announced a 35% tariff on Canadian goods.

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.

U.S. stock futures fell Sunday, a day after President Donald Trump threatened to impose new 30% tariffs against imports from Mexico and the European Union.

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