Imagine if a country decided to shut down its nuclear power plants due in part to safety concerns, but decided to keep hosting nuclear weapons on its own soil. One doesn’t have to, because that’s exactly what Germany has done. Since 1955, the country has been part of a US nuclear weapons-sharing scheme and hosts an estimated 20 B61 gravity bombs at Büchel airbase in the Palatinate. These bombs are under US control, but would be carried and dropped by German aircraft.

Germany obviously isn’t going to win a nuclear war with this small arsenal, and it’s clearly something that has been troubling Friedrich Merz. The German Chancellor has been talking about the need for a shared nuclear umbrella programme which doesn’t rely on the US. The current presence of American nuclear weapons on German soil brings the country solidly into the so-called “nuclear umbrella” that the US, with its much larger arsenal, provides to allies. This is the difference between a genuine nuclear umbrella and vague, somewhat unreliable assurances that the US will start Armageddon if Russia totals Potsdam.

Despite this, the German government has become worried about the American nuclear umbrella’s reliability due to Donald Trump’s recent erratic behaviour, which has put the future of the Western alliance in doubt. That’s why it’s no surprise that Merz wants to pivot to a Europe-wide nuclear umbrella. This wouldn’t see Germany develop its own nuclear weapons, though it certainly could in terms of finances and the knowledge of nuclear weaponry. But legally, politically, and diplomatically, it would be a non-starter. Germany is party to not one but two treaties which preclude it from developing its own nuclear weapons: the Two Plus Four Treaty that established a reunified Germany, and the UN’s Non-Proliferation Treaty.

Instead, Germany will explore using the nuclear capabilities of other European countries — Britain and France — to form a new umbrella. But this plan comes with major flaws of its own. Firstly, the UK’s own nuclear arsenal depends heavily on US technology, meaning that it couldn’t be truly independent in the way that Germany would presumably require. That leaves France.

At the moment, France’s nuclear doctrine does mention that its “vital interests” — any justification for launching a strike — have a “European dimension”, which may include the security of its close neighbours. This is hardly a nuclear umbrella, and brings us back to the vague assurances level.

If Merz is listened to and there are developments on the discussions over a European nuclear umbrella, would it be feasible to replace the current American version? Even if France had the will to extend its arsenal to neighbouring European countries, that would be a tall order. Its number of warheads is small compared to the US — France has roughly 300, compared to America’s 5,000 — and its delivery options are limited. This level of nuclear protection is fine for defending France, but would not come close to being an American-style umbrella for the whole of the continent.

Whether this could change with European support depends on the terms of a potential deal. It’s hard to imagine France turning down a German-led offer to pay for some of its nuclear programme, but only on the proviso that it retains the final say over when and under what circumstances it’s launched. That’s not too dissimilar to the arrangement with the US. The main difference would be that France is tied much more closely to Germany’s defensive interests than the US is.

If Germany were to come under threat, it’s likely that the whole of Europe, including France, would be implicated in some way. But the US giving the orders is more politically palatable than France doing so. If Merz does want a nuclear umbrella, he won’t be able to drift away from America anytime soon.

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