U.S. President Donald Trump on Thursday signed an executive order increasing tariffs on Canadian goods to 35% from 25% on all products not covered by the U.S.-Mexico-Canada trade agreement, the White House said.

The imbalance in President Trump’s treatment of America’s closest trading partners may come from his desire to make Canada the 51st state, some Canadians believe.

Trump’s promise to impose 30% tariffs on imports from Mexico and 35% on imports from Canada beginning tomorrow could hammer up to three-fourths of their U.S. imports.