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.

The trade war between the US and Canada has escalated sharply with President Donald Trump increasing the tariff rate on Canadian imports from 25% to 35%. Most goods will avoid the increased costs entering the US market because they are protected by a trade treaty.