Days after US President Donald Trump announced the withdrawal of roughly one third of US troops stationed in Germany, the shock still lingers.

Politicians at every level are grappling with the consequences: Mayors in economically weak regions are worried about losing income when the GIs leave, Germany's foreign minister is worried about the further deterioration of relations with the US and military planners in Brussels are pondering the implication for Europe's own security architecture. Germany has been a key component of the US defense strategy in Europe for decades, with US nuclear weapons — to be delivered by German fighter jets in a moment of crisis — stationed here.

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But if the roughly 9,500 US soldiers go home rather than head somewhere else in Europe, it will radically shift military relations on the continent. "It is entirely unclear where this journey is heading and what security risks lie ahead," said Thomas Kleine-Brockhoff, vice president of the Berlin-based German Marshall Fund, a non-partisan trans-Atlantic think tank.

Kleine-Brockhoff said he can't make out a winner yet, not even neighboring Poland, which can realistically maintain hopes of an increased US troop presence. He told DW the weakening of ties between Germany and the US is damaging to the whole of Europe, and Central and Eastern European countries have taken note.

European security without American might

"Europe will have to take on more responsibility," said Roderich Kiesewetter, a former military officer who is now a parliamentary foreign policy expert for Angela Merkel's Christian Democratic Union party. That statement echoes demands often made by relevant department heads and by the chancellor herself. Still, when it comes to defining what that new European role might be, German policymakers prefer to leave all of their options open.

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Might that mean Germany and Europe would take the burden of smaller crisis regions off American shoulders, allowing the US to focus on Asia and rival China? Or will the German government succumb to years of pressure from the US and NATO to increase defense spending and finally pass massive military budgets?

That latter is exactly the approach backed by foreign policy expert Kleine-Brockhoff. "During the refugee and coronavirus crises the German government has shown it is willing to allocate huge sums of money," he pointed out.

Or is Germany ready for a paradigm shift — working toward a Europe that can protect itself, without the US?

Repeated overtures

Should that final option be the secret desire of German politicians, it would no doubt bring out every last EU political and military heavyweight between Berlin and Paris. And it would also put the spotlight on an uncomfortable issue for the Germans: their stance on nuclear weapons — which are, after all, considered the last guarantor of independent sovereignty.

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Germany has been under the protection of NATO's nuclear umbrella — and thus also the US — for decades, and if Europe wants to provide its own security it will have to come up with a replacement shield. As things stand now, France would be the only choice in stepping up to the task. France has not been shy about splurging on its "Force de frappe" nuclear strike force. But French leaders have also been careful to maintain distance to NATO and the US on that front: French missiles have never been integrated into NATO defense planning.

Nevertheless, in the past the French have made clear their willingness to allow Germany proximity to its prized arsenal. In the 1990s, President Jacques Chirac even considered the concept of joint responsibility. And during his term, Nicolas Sarkozy is said to have offered Merkel a financial stake in the program. At the time, the Germans thanked the French for their offer but refused, with a nod to the US shield.

Macron's opening

Earlier this year, President Emmanuel Macron made a new proposition, inviting his European partners to take part in a "strategic dialogue" on France's nuclear weapons. Though it was unclear how the offer should be taken, the German Defense Ministry accepted the invitation during a meeting in Paris — though not without stressing the significance of the US umbrella while doing so.

Four months on, the public has yet to see any of the fruits of that meeting. A Defense Ministry spokesman would only go so far as to confirm that "the question of a nuclear deterrent in Europe was addressed within the framework of regular rotating discussions on various strategic issues."

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The fact that there have been no public announcements no doubt has to do with the sensitivity of the issue of nuclear deterrence. "When the US umbrella and its nuclear posture in Europe and other places is called into question," said Kleine-Brockhoff, "a lot of small and medium-sized countries will feel the need to become nuclear powers themselves." Uncertainty alone could set off a chain reaction among partners and rivals alike.

Still, the issue of whether or not to create a European nuclear umbrella could well arise should Trump complete a US withdrawal from Europe that started long before he came to office. "I would advise the government to take a two-pronged approach," said Christian Mölling, a security expert at the German Council on Foreign Relations, a Berlin-based think tank. He said they should "keep their option to move to the French system open," but added that such a major shift would take decades.

Weapons system the start of something bigger?

The Future Combat Air System (FCAS), a Franco-German project to develop a complex air-based defense system by 2040 — one that will play a key role in the French deterrence strategy — could prove a good opportunity to deepen trust. "Twenty years to build trust and a shared perspective — that's not a lot of time. At least not for fundamental change in policy direction," said Mölling.

Beyond the obvious technical challenges, a look at both partners also illustrates how disparate mindsets within the cooperation can be: Nuclear deterrent is the heart of France's security architecture, while in Germany some politicians are calling for the withdrawal of all US nuclear weapons.

The one seemingly intractable conflict inherent in the idea of a "European bomb," however, is the question of who would decide to use it when a split-second decision is needed. In France, that duty falls to the president, who is closely followed everywhere he goes by an officer carrying the nation's nuclear codes.

There are no easy answers, but Germany will likely have to get used to the French nuclear mindset in the coming years. Establishing independent European security — if such a thing is possible — would take years to realize. But it's never too early to start thinking about it.