U.S. President Donald Trump on Friday signed orders expanding credits for U.S. auto and engine production and setting new 25% tariffs on imported medium- and heavy-duty trucks and parts starting Nov. 1.

The tariffs, which the orders say are being made on national security grounds, are aimed at shifting more auto production to the United States but could be a significant blow to Mexico, which is the largest exporter of medium- and heavy-duty trucks to the United States.

Trump is also setting a 10% tariff on imported buses.