Defending Europe without the United States: a guide and the challenges to overcome

At the NATO summit in The Hague in June 2025, one scene summed up the state of the Atlantic Alliance better than any speech: according to observers present, European leaders found themselves waiting for instructions from a single man. Donald Trump demanded that his allies raise their defence spending to 5% of their GDP by 2035, and the Europeans complied, meekly, taking great care to avoid mentioning Ukraine. The contrast was striking: on one side, the greatest military power in history, which still accounts for nearly 70% of the Alliance’s total expenditure; on the other, a continent which, after three decades of the peace dividend, is anxiously rediscovering what it means to ensure its own security.

Since Trump’s return to the White House in January 2025, the question is no longer hypothetical. Vice-President J.D. Vance humiliated the Europeans in Munich, Washington suspended its aid to Ukraine without consultation, and documents revealed by Politico show that contingency plans have been quietly drawn up in Brussels for a scenario of complete US withdrawal. Added to this, in February 2026, was an even deeper rift: the United States and Israel struck the Iranian regime, and Trump demanded that NATO join the offensive to reopen the Strait of Hormuz, which had been closed by Tehran. The Europeans refused, with France and Spain going so far as to close their airspace to US aircraft transporting military equipment to Israel. The transatlantic rift is now a fait accompli.

On 1 April 2026, Donald Trump crossed a new threshold. In an interview with the British daily The Telegraph, the US president stated that he was “strongly” considering a US withdrawal from the Atlantic Alliance, describing NATO as a “paper tiger” and claiming he had “never been convinced” by the organisation. His Secretary of State, Marco Rubio, immediately followed suit, declaring on Fox News that Washington should “re-examine” its relationship with the Alliance, describing it as a “one-way street”.

Can Europe be defended without the United States? The honest answer is: not yet, not completely, not tomorrow. But Europe possesses more resources than it realises, and the missing pieces have been identified. What is lacking most is the political will to put them together, and the time to do so.