Former U.S. President Donald Trump stirred global headlines again on May 28 with a provocative message posted on his platform, Truth Social. This time, his target was Canada. Trump proposed that if Canada wants to join the proposed “Golden Dome” missile defense program, it has two options: pay a steep entry fee of $61 billion—or give up its national sovereignty and become the 51st U.S. state, thus gaining free access to the system.

Trump’s post read: “I told Canada that if they want to remain ‘independent but unequal,’ they’ll have to pay. But if they choose to become part of our family—as I call it, the 51st state—that fee is waived.” He even claimed that Canada is “seriously considering” the offer.

Canadian Prime Minister Mark Carney, however, was quick to push back. He confirmed Canada’s interest in missile defense and acknowledged that high-level talks are ongoing with the U.S. But he firmly stressed that Canada is “not for sale” and will not compromise its sovereignty. Cooperation, yes—but not at the cost of national identity.

This exchange comes at a time when Canada is actively pursuing stronger security ties with Europe. Carney recently announced Canada’s intention to join a European defense realignment plan before July 1, and questioned the current Canada-U.S. defense spending balance: “For every dollar we spend on defense, about 75 cents ends up going to American companies. Is that sustainable?”

The “Golden Dome” plan aims to build a cutting-edge defense network by 2029, integrating satellite surveillance and missile interception technology to guard against global and even extraterrestrial threats. The project’s estimated budget stands at $175 billion, though some analysts say the real cost could exceed $500 billion.

Experts in government and defense emphasize that Canada’s involvement is essential, particularly due to its vast northern radar and airspace resources—key to monitoring potential threats from Russia and China. Without Canadian cooperation, the viability of this U.S.-led initiative could be seriously in doubt.

Trump’s statements have added fresh tension to the already complex U.S.-Canada relationship. His administration was never particularly gentle with its northern neighbor, having previously threatened tariffs and expressed ambitions to expand American influence. While a recent White House meeting attempted to ease strains from past trade disputes, the new “51st state” rhetoric may set things back again.

Although the U.S. and Canada have long cooperated on continental defense through NORAD, Trump’s framing of integration as a condition of participation—implying political unification—pushes beyond the traditional bounds of allied relations.

Adding to the political undertone, King Charles III delivered a speech to Canada’s Parliament the same day, subtly underscoring Canada’s strength and identity: “A confident Canada has a deeper essence than anything a foreign power can take away.” Carney later reposted the clip with the caption: “The true North, strong and free.”

As Arctic strategy becomes ever more critical amid rising tensions between the U.S., China, and Russia, North American defense cooperation will only gain importance. But it must be rooted in mutual trust and respect—not ultimatums.

In the coming months, all eyes will be on how Canada responds to the Golden Dome proposal and what moves Washington makes next. For other Western allies, this moment raises a fundamental foreign policy question: follow Washington’s tech-driven vision, or stand up for smaller nations’ sovereignty?