President Donald Trump said he’s terminating trade negotiations with Canada citing a negative TV advertisement about tariffs.

“They only did this to interfere with the decision of the U.S. Supreme Court, and other courts,” Trump said of the Canadian advertisement in a post on his social media platform. “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.”

In a White House meeting with Canadian Prime Minister Mark Carney earlier this month, Trump signaled optimism about a potential U.S.-Canada trade deal, saying the two sides had “come a long way” in negotiations.

In July, Trump issued a 35% tariff on most goods and raw materials from Canada.

This is a developing story. Please check back for updates.