Trump’s NATO Threat Leaves Europe Facing Its Own Rearmament Problem

Trump revives a familiar threat

Donald Trump has once again thrown transatlantic relations into a spin by saying he is “seriously considering” pulling the United States out of NATO. In an interview with The Telegraph published on Wednesday, April 1, he described the alliance as a “paper tiger” and added, with his usual gift for diplomacy, that “Putin knows it too, by the way.”

That set off a quick exchange with British Prime Minister Keir Starmer, who insisted NATO is “the most effective military alliance the world has ever seen.” Trump’s response was predictably warm: the United Kingdom, he said, “doesn’t even have a navy anymore”, while Starmer was supposedly more interested in building “windmills.”

This is not exactly new territory. Trump has threatened disengagement before. To head that off, NATO members agreed last June to spend 5% of GDP on defense by 2035. The calculation was straightforward: give Trump a number, hope he likes it, and maybe he stops treating the alliance like a subscription he can cancel.

The pressure has only grown after the allies’ refusal to back the United States and Israel in Iran. Trump called that a “failed test” and said he was “very disappointed.” If that mood hardens, the consequences could also reach Kyiv, where promised weapons deliveries may be slowed or redirected, beginning with what is available in Pentagon reserves.

Why Europe would feel the shock first

If the United States really did leave NATO, the biggest problem would not be the alliance itself. It would be the European Union, which for seven decades has largely outsourced its security to Washington.

As Federico Fabbrini, professor of EU law in Dublin and currently a Fulbright Schuman Fellow in International Security at Harvard, told Il Fatto Quotidiano, the EU had effectively grown used to peace. In his view, the bloc’s defense model reflects that habit: a fragmented system in which national security remains the exclusive responsibility of each member state, while the EU mostly plays a supporting role.

That arrangement held until the war in Ukraine and Trump’s return forced Europe to confront reality. Brussels responded with new tools, but many of them are built on shaky institutional foundations and limited money. In other words, they were designed by structures that were themselves designed for calmer times. A classic European specialty.

Fabbrini explores these limits in his book L’esercito europeo – Difesa e pace nell’era Trump (The European Army - Defense and Peace in the Trump Era), published by il Mulino in 2026.

Europe’s defense tools: ambitious, awkward, incomplete

One of the main examples is ASAP (Act in Support of Ammunition Production), adopted in 2023 with €500 million to provide one million shells to Ukraine within a year.

That goal, Fabbrini argues, failed dramatically. The EU reached only about a third of the target. Part of the problem was institutional: the Council stripped the Commission of any real power to steer the defense industry, instead relying on market players to cooperate out of goodwill. That approach predictably delivered less than the slogans promised. The acronym itself, which conveniently also means “as soon as possible,” turned out to be the joke.

Then there is SAFE (Security Action for Europe), approved by the Council on May 27, 2025, with a ceiling of €150 billion. But SAFE does not hand out grants. It provides loans, which member states must repay with interest.

The case of Poland is revealing. SAFE was widely seen as designed with Warsaw in mind, yet Fabbrini notes that the Polish president vetoed the prime minister’s request to access the funds because of internal political tensions. So much for seamless European unity.

Another sign of delay is the proposed rapid reaction force of just 5,000 troops. It took three years to formalize, and it still has not been deployed. According to Fabbrini, the problem is a mix of national rivalries and a defense market that remains effectively outside the EU’s internal market. That leaves national industries protected, with monopoly-like positions and the freedom to set prices as they please.

The “coalition of the willing” and its limits

After Trump’s threats intensified, a so-called coalition of the willing was launched on March 2, 2025, at the initiative of France and the United Kingdom. The aim was to provide Ukraine with a “reassurance force.”

Fabbrini is skeptical. He compares the format to a “party of friends”: people come and go, commitments stay vague, and nobody is truly signing up for anything concrete. That may be fine for planning a dinner. It is less convincing when the subject is sending troops into a situation where men and women could die.

As the book puts it, decisions made in an intergovernmental forum are inherently fragile, which makes them hard to believe when directed at third countries. In short, Europe still lacks the legitimacy, and the political structure, to make a truly binding decision on collective military deployment.

Germany’s sudden sprint

Into that vacuum steps Germany.

In just one month, Berlin changed its Basic Law to allow unlimited borrowing for defense. A year ago, Chancellor Friedrich Merz announced plans to invest €1 trillion over the next 10 years, saying plainly that the Bundeswehr would become the “most powerful conventional army in Europe.”

Fabbrini describes this as one of the most historic paradigm shifts in postwar German history. The speed of the change, and the scale of the fiscal expansion behind it, he says, are reminiscent of German reunification.

Germany’s advantage is simple enough: it has the fiscal strength to pull off a real rearmament. Most of its partners do not. That makes Berlin’s move both impressive and awkward. If Germany goes ahead alone while the rest of the EU remains constrained by weak finances and messy governance, the result could be deep asymmetries inside the Union.

For countries such as Italy, Fabbrini warns, that could mean a minor role in the new defense order. It would also push, once again, the long-discussed but still shelved idea of an integrated European defense force further out of reach.

The EU has had that project on its books since 1951. It has simply spent most of that time in a drawer.