WASHINGTON (AP) — President Donald Trump announced he’s ending “all trade negotiations” with Canada because of a television ad opposing U.S. tariffs that he said misstated the facts and was aimed at influencing U.S. court decisions.

The post on Trump’s social media site came Thursday night after Canadian Prime Minister Mark Carney said he aims to double his country’s exports to countries outside the U.S. because of the threat posed by Trump’s tariffs. Trump’s call for an abrupt end to negotiations could further inflame trade tensions that have been building between the two neighboring countries for months.

Trump posted, “The Ronald Reagan Foundation has just announced that Canada has fraudulently used an advertisement, which is FAKE, featuring Ronald Reagan speaking negatively about Tariffs.”

The ad was paid for by the Ontario provincial government, not the Canadian federal government. The Ontario government said it planned to pay $54 million (about $75 million Canadian) for the ads to air across multiple American television stations using audio and video of then-President Reagan speaking about tariffs in 1987.

“They only did this to interfere with the decision of the U.S. Supreme Court, and other courts,” Trump wrote on his social media site. “TARIFFS ARE VERY IMPORTANT TO THE NATIONAL SECURITY, AND ECONOMY, OF THE U.S.A. Based on their egregious behavior, ALL TRADE NEGOTIATIONS WITH CANADA ARE HEREBY TERMINATED.”

Ontario Premier Doug Ford didn’t back down, posting on Friday that Canada and the U.S. are friends, neighbors and allies “and Reagan knew that both are stronger together.” Ford then provided a link to a Reagan speech where the late president voices opposition to tariffs.

Carney said his government remains ready to continue talks to reduce tariffs in certain sectors.