The tariff battle between the United States and Canada could turn into a feedback loop if President Donald Trump follows through with a new threat to levy another round of retaliatory tariffs against the northern country.

The U.S. hit Canada with 25% tariffs Tuesday morning, after which Canadian Prime Minister Justin Trudeau announced his country would impose 25% retaliatory tariffs going back the other way. But Trump threatened Tuesday afternoon that new import duties could swing right back around to Canada again.