In agreeing the “framework of a future deal” with Donald Trump over Greenland on Wednesday, Mark Rutte may have bought the European Union more time. While he has in this case demonstrated more diplomatic nous than other European politicians, there’s a previous Rutte moment which is far more indicative of his political capability. In 2020, he raised the idea of an EU without Hungary or Poland. It was a seismic moment that perhaps showed a narrow range of ideological flexibility within the bloc. A similar but far more difficult and consequential idea is now taking hold within European defence policy: Nato, but without the United States.

According to reports in Europe, discussions are already taking place about this possibility. There are clearly big problems with the immediate logistics and how long the decoupling process could feasibly take, but the main issue concerns whether this would truly rid Europe of its US dependency. The intergovernmental model of which Nato is a representative example, born in the middle part of the last century, might have worked at its inception. Now, however, in a time of defence-industrial supply chains and resource-intensive technological development, that relevance is fading.

In the modern geopolitical landscape, Nato is just a cog in the kind of military coordination and assurance structures which ensure Western security. The European dependence on Washington for its defence needs not only revolves around US security guarantees, such as Nato’s Article 5, but is a byproduct of those guarantees. The US military itself is large, but the country’s military-industrial complex is enormous, producing vast quantities of equipment. Europe is left to rely on how advanced that equipment is.

There’s been some debate over exactly how much American-made military equipment Europeans provide, versus what is produced domestically. But, as a paper from the think tank Bruegel pointed out last year, the raw numbers don’t give a clear picture of the scale of dependence on US production. One reason for this is that even when Europeans buy domestically, what they are buying is often from American producers — or partnerships between American and European firms. Another is that Europe still often relies on the US for key enablers, such as software. For example, Britain uses Amazon Web Services as part of its UK National Security and Defence programme, something which, due to its level of integration, would be hard to wean off.

This presents obvious vulnerabilities, especially if European governments do something with this equipment that the US doesn’t support — or even if there’s something a Nato country does of which America doesn’t approve. There has been much speculation about so-called kill switches in US-provided weapons systems. But there are numerous other ways the US could quickly make European weaponry useless, with anything from denying maintenance support to stopping software updates potentially being used against Nato.

Dealing with this requires more than just a new intergovernmental body without the United States. For a start, Europeans would need to procure defence equipment jointly at a larger scale, which would match the current capability of the US. This would then enable Europe to make advanced defence projects more feasible and boost order volumes for domestic companies. The continent would also need to focus on addressing its serious technology gap with the US. If Trump’s actions over the past few weeks show anything, it’s that the US can’t be relied on forever as the backbone to Nato’s defence. But if Europe’s defence policy shows anything, it’s that Brussels is not ready to go its own way when it comes to security.

This is an edited version of an article which originally appeared in the Eurointelligence newsletter.