Recent disclosures that Canadian military officials conducted war games simulating a potential U.S. invasion earlier this year have shed light on the complexities and tensions underlying the Canada-U.S. defence relationship. Prime Minister Mark Carney described the scenario as an “extreme tail risk” in an interview, emphasizing that it was not an expectation but a prudent planning measure.

Amid ongoing tariff disputes and geopolitical challenges—including threats in the Arctic, missile proliferation, and drone activity—questions have emerged about the strength and future of continental defence cooperation. In an interview, retired General Glen VanHerck, who led the U.S. Northern Command and North American Aerospace Defence Command (Norad) from 2020 to 2024, provided insight into how these political frictions influence military collaboration.

According to VanHerck, day-to-day defence operations between the two countries remained largely unaffected despite political disagreements, particularly on trade. However, he acknowledged that such disputes sometimes cast doubt on the political will to fully support shared military commitments, including Norad modernization efforts. He pointed to delays in strategy implementation and unfulfilled funding commitments from the Canadian government under prior administrations as factors that raised concerns about long-term support.

VanHerck expressed confidence that current trade tensions would not directly undermine military cooperation but noted that financial constraints and resource limitations could impact Canada’s ability to maintain interoperable and integrated platforms. He underscored that Canada’s geographic position, especially in the Arctic, and its political commitment to a binational defence arrangement were irreplaceable elements of North American security.

Reflecting on Prime Minister Carney’s affirmation of increased support for Norad funding, VanHerck said the current administration had advanced financial commitments that had previously stalled. On the NATO defence spending benchmark of 2 percent of GDP, he suggested that arbitrary spending targets offer limited value without considering the actual threat environment and stability needs.

Regarding the revelation that Canada war-gamed the possibility of a U.S. military invasion, VanHerck expressed surprise and some concern. While he emphasized that military planners should prepare for all conceivable contingencies, he found the notion of a U.S. invasion unexpected given the historically close relationship between the two countries. He noted that no indicators existed to suggest such an invasion was likely or being considered, viewing the scenario as more a reflection of political rhetoric than operational reality.

VanHerck also confirmed that while U.S. military exercises have included moving forces into Canadian territory to support joint missions under Norad, planning for hostile action from Canada had never been part of U.S. exercises during his tenure.

Overall, VanHerck assessed that the military trust and cooperation between Canada and the U.S. remain strong. He highlighted ongoing mutual respect and collaboration among senior leaders on both sides and reiterated the commitment to their joint continental defence mission despite the political and economic challenges that occasionally arise.