The congratulations from European leaders to President-elect Donald Trump are flowing like champagne, which is incidentally how Hungarian Prime Minister Viktor Orban planned to celebrate. Those on the nationalist and euroskeptic end of the political spectrum are feeling energized; those on the left are no doubt tweeting through gritted teeth. Over in France, America’s oldest ally, the mood is conflicted: President Emmanuel Macron’s English tweet offering to “work together” with Trump was followed up by a French-language tweet stridently promising a stronger, more united Europe.

Yet no amount of Trump-whispering changes the fact that the Old Continent looks woefully defenseless in the face of the coming geopolitical storm. A MAGA-Republican White House and Congress would bring the risk of more “America First” spending, punitive tariffs on European imports and fights over taxes and red tape on U.S. tech (including Elon Musk’s.) Trump has also put collective defense under NATO’s Article 5 on notice by making it conditional on spending; his preoccupation is China, not Ukraine. The slow agony of Europe’s economic and productivity decline under Sino-American pressure makes it hard to picture a robust response, as does the soft-power-led continent’s reliance on U.S. security.

A stark choice awaits the European Union’s 27 members along with neighbors like the UK. Leaders can adopt the typical muddle-through treatment, lining up to pay homage to Trump and seek preferential treatment through deals or (more likely) concessions, prolonging the status quo of a lopsided relationship with a U.S. that increasingly doesn’t care about a continent stuck in economic and demographic decline. This might offer an extension of what the International Institute for Strategic Studies’ Francois Heisbourg calls les trente paresseuses — the 30-year geopolitical slumber typified by Germany’s model of free-riding on U.S. defense, China trade and Russian gas while leaving defense spending and strategic credibility to wither.

Or it could try more assertiveness and investment — starting with defense — that would allow for better burden sharing, more independent support for Ukraine’s search for a “just peace” and a more balanced relationship with Trump’s America.

I appreciate this kind of talk is starting to sound more like theology than reality. It’s been almost a decade since Macron rode into power with all kinds of promises of sovereignty and strategic autonomy — yet even today, with the largest full-scale conflict on European soil since 1945, South Korea has supplied more shells to Ukraine than all of Europe, and Musk’s Starlink is the technological game-changer. As Zbigniew Brzezinski, who served as President Jimmy Carter’s national security adviser, once said, Europe is a U.S. protectorate with a deep economic dependency. This doesn’t just get thrown off one day.

Still, there are the faintest hints of change afoot. Trump symbolizes a security deal that looks less appealing to both sides: The U.S.’s pivot to Asia means 100,000 of its service members in Europe are no longer a no-brainer, as Trump himself has warned, while for the continentals the historically pitiful amounts spent by the likes of Germany on defense look like a liability as Russia’s war economy whirs. Hence why that spending is going up: European NATO members’ military outlays are set to rise by $33 billion this year to $380 billion, hitting 2% of gross domestic product, with Poland the biggest individual contributor relative to GDP. That doesn’t signal readiness, with €500 billion in EU defense spending needs over the next decade. But Europe is at least set to match Russia’s ammunition production next year.

This wake-up call isn’t just coming from the usual suspects — ahem, France — but Europe’s own “swing states” with once-unshakable faith in the US. Poland’s Prime Minister Donald Tusk recently tweeted that “the era of geopolitical outsourcing is over,” Estonia’s former Prime Minister Kaja Kallas has thrown her support behind joint EU defense funding and Lithuania’s ex-Prime Minister Andrius Kubilius has been given the new job of European commissioner for defense and space. Germany’s reticence is a key stumbling block, but Friedrich Merz, frontrunner to be the next chancellor, has taken a strong pro-Ukraine line and is calling for EU solutions as the U.S. turns inward.

There are still crucial pieces of the puzzle missing. Europe has a strong defense-industrial base, including the likes of Rheinmetall AG and Airbus SE, but it needs more contracts, less fragmentation and modernized procurement systems in a more tech-driven world. It also needs faster decision-making: Former French and Moldovan ministers Laurence Boone and Nicu Popescu are arguing for a European version of the U.S. Defense Production Act to speed up responses in crises. And given fiscal constraints, there’s a renewed case for defense bonds that would increase spending, make it more efficient and encourage coordination, the Center for European Reform argues.

While the trans-Atlantic relationship has a multitude of issues, everything flows from defense: It is both a direct cause of tension because Europeans aren’t pulling their weight and an indirect one because it gives Trump lever to extract concessions elsewhere. More defense means more autonomy, more credible geopolitics and a healthier industrial base. If the old ways win instead — and the risk of this is high — then the coming geopolitical winter will be incredibly cold.

Lionel Laurent previously was a reporter for Reuters and Forbes.