President Donald Trump revoked Canada’s invitation to participate in his “Board of Peace” initiative, in the latest blow to the increasingly frosty relations between the North American neighbors.

Trump said in a social media post on Thursday that Canadian Prime Minister Mark Carney would no longer be welcome on the board, which his administration initially created to oversee the end of the war in Gaza but has since said would have a broader mission.

The president did not specify why he was withdrawing the invitation to Carney, but his social media post came after the prime minister raised concerns about the board and pushed back sharply at Trump’s remark that “Canada lives because of the United States” in a speech at the World Economic Forum in Davos, Switzerland on Wednesday.

“Canada doesn’t live because of the United States. Canada thrives because we are Canadian,” Carney said earlier Thursday.

The Canadian prime minister’s office had no immediate comment on Trump’s announcement.

The withdrawn invitation deepens the fracture in the relationship between Trump and Carney, who stood with other NATO allies in opposition to the president’s campaign to wrest control of Greenland from Denmark.

The two leaders appear to be working towards opposing geopolitical goals: Carney travelled to China to negotiate a trade deal as part of a mission of ramping up trade with non-U.S. partners to decrease reliance on its neighbor.

The tension sets the table for a potentially tense review of the U.S.-Mexico-Canada trade agreement later this year.

In announcing the U.S. plan for governance of Gaza, Trump said he expects over 50 countries to sign on to the plan. Some Middle Eastern nations, including Israel and the United Arab Emirates, have agreed to join the board.

But many Western allies have yet to sign on, and France and the United Kingdom have said they will not participate in the plan. Yvette Cooper, the U.K.’s top diplomat, cited Trump’s invitation to Russian President Vladimir Putin as part of the reason the U.K. won’t sign on.