Canada and the five Nordic countries have vowed to seek closer “middle power” cooperation, a strategic effort to preserve national sovereignty. The move exposes a rift in the U.S.-led alliance system, which faces multiple uncertainties, including internal coordination challenges and U.S. pressure.

Middle powers on the continent have a real motivation to cooperate. Constrained by structural factors such as their defense systems, however, the so-called transatlantic shared heritage and the scale of the U.S. market, their cooperation is seen mostly in policy coordination and diplomatic statements.