The Pentagon is pausing a decades-old U.S.-Canada defense forum in a fresh sign of frayed ties between Washington and Ottawa over security spending.

Canada finally hit NATO’s longstanding target of 2% of GDP last year, with pledges of major investments in submarines, fighter jets and Arctic security. But Prime Minister Mark Carney has said in recent weeks that the country will spend less on defense spending in the U.S. as it builds its own industry.

“The days of our military sending 70 cents of every dollar to the United States are over,” Carney said April 11 at the Liberal Party’s national convention in Montreal.

The Trump administration may be striking back. On Monday, the Pentagon announced it was halting the Permanent Joint Board on Defense while officials reassess “how this forum benefits shared North American defense.”

“A strong Canada that prioritizes hard power over rhetoric benefits us all,” Elbridge Colby, the Pentagon’s policy chief, wrote on X. “Unfortunately, Canada has failed to make credible progress on its defense commitments.”

The Permanent Joint Board on Defense, established during World War II, serves as a bilateral advisory body on U.S.-Canada defense policy. It’s been historically used to address issues such as cost-sharing for continental defense systems, including the North Warning System.

Erin O’Toole, a former leader of the Conservative Party of Canada, panned the move as “profoundly misguided and quite strange.”

“Canada has been and will be an ally that shares values of liberty,” he wrote on X. “As a Canadian whose grandfather deployed to Alaska for joint defence in WWII, I hope we don’t lose sight of that.”

U.S.-Canada relations have been strained in recent months after President Donald Trump repeatedly suggested that Canada should become the 51st state and called for the U.S. to take control of Greenland, the autonomous Danish territory.

Last year, Carney initiated a review of plans to purchase 88 Lockheed Martin-made F-35 fighter jets. Pete Hoekstra, the U.S. ambassador to Canada, later told the CBC that if Canada does not follow through with the purchase, the defense partnership between the two countries, NORAD, “would have to be altered” — with more U.S. flights in Canadian airspace.

Canada remains tied near the bottom of NATO countries on defense spending as a share of economic output, alongside Belgium and Spain. NATO allies, under pressure from Trump, agreed last year to a new target of spending 5% of GDP on defense and security by 2035.

Canada has stepped up cooperation with subsets of NATO allies, including the Nordic countries, the U.K., the Netherlands and Germany, to protect what Carney called, “our Arctic.” In March, Carney announced more than $20 billion for forward-operating locations and infrastructure in the North to assert sovereignty over the increasingly contested region.

Retired Gen. Glen VanHerck, former commander of NORAD and U.S. Northern Command, said the pause likely reflects frustration with the pace of Canada’s defense spending. Washington may be seeing faster progress on projects such as over-the-horizon radar, anti-submarine warfare, and other homeland defense capabilities.

“I think a message to the government of Canada that hey, we’re serious, we’d like you to move faster,” he said. “You’ve made verbal commitments. Now, we need to see action.”

Still, Canada paid 40% on much of NORAD’s last modernization effort. “I wouldn’t look at them as a country that has been free riding on the United States,” VanHerck said.

Canada’s embassy in Washington did not immediately respond to a request for comment.

This story has been updated with additional information.