Plan B: Europe accelerates NATO contingency plans amid fears of a US withdrawal

Plans to safeguard the ability of Europe to defend itself using NATO's existing military structure in the event that US President Donald Trump withdraws the US out of the alliance are gaining momentum after securing support from Germany, which had long opposed a unilateral approach.

According to a report in the Wall Street Journal (WSJ), the officials behind the plans, referred to as "European NATO" by some, are already working on getting more Europeans into the alliance's command-and-control roles and supplementing US military assets with their own.

Where did the idea come from?

The idea of a more self-dependent, less US-reliant defense structure of Europe is nothing new.

But the growing hostility of Trump towards NATO has made many in Europe question how reliable a partner the US really is.

The first shift was a stark change in support for Ukraine: diverging from the stance of other European NATO members, the new Trump administration moved away from the "as long as it takes" approach toward increased pressure on Kyiv to end the conflict, regardless of the cost.

However, the main source of European anxiety over US commitment to the alliance stems from Trump's threats to seize Greenland from fellow NATO member Denmark and, more recently, the standoff over Europe's refusal to back America's attack on Iran.

Earlier this month, tensions between Washington and NATO allies flared up as Trump said he was considering pulling the US out of the military alliance due to its European members' refusal to send ships to unblock the Strait of Hormuz.

And while any withdrawal from the alliance would require congressional approval, the president could still move troops or assets out of Europe or withhold support using his authority as commander-in-chief.

It is this eventuality that the European plans are meant to tackle.

What would a 'European NATO' look like, and what challenges would it face?

Rather than to rival the current alliance, European officials seek to sustain deterrence against Russia, ensure operational continuity, and uphold nuclear credibility – even if Washington withdraws its forces from Europe or declines to come to its defense.

But while Germany's decision to come on board marks a major development, the plans for "European NATO" face several major challenges.

Current NATO's entire structure is based around American leadership at virtually every level, ranging from logistics and intelligence to the alliance's top military command.

And while Europeans are starting to shoulder more responsibilities and stepping into more leadership roles, they still lack critical capabilities due to years of underspending and reliance on the US.

In raw military terms, even without the United States, NATO would still be a very large force.

A recent assessment by the Center for Strategic and International Studies (CSIS) estimates that European NATO countries have 1.86 million active military personnel, suggesting that Europe's challenge lies less in overall numbers than in readiness, coordination, and the ability to deploy rapidly.

After all, the US is not just another large ally within the alliance; it remains the single largest military contributor, both in overall spending and in many of the capabilities that enable NATO to operate at speed.

According to NATO's latest annual report, the US accounted for 60% of total alliance defense expenditure in 2025, with Europe and Canada together making up the remaining 40%.

One of the many areas where Europeans lack in comparison to their American counterparts is high-end airpower.

Drawing on the International Institute for Strategic Studies report The Military Balance 2025, CSIS estimates that the United States fields around 3,300 combat-capable aircraft, compared with roughly 2,100 across the European NATO members in its dataset, which excludes Türkiye.

While European allies would still retain substantial land forces, major navies, advanced combat aircraft, and two nuclear powers in the UK and France, they would lose a disproportionate share of their most advanced, deployable, and integrated military capabilities.

But perhaps the greatest challenge comes in the form of Europe's reliance on the United States to provide the continent-wide nuclear umbrella that underpins the alliance's founding principle of deterrence through strength.

Discussions are already under way, prompted in part by Trump's threats to invade Greenland, between German Chancellor Friedrich Merz and French President Emmanuel Macron on whether France's nuclear deterrent could be extended to cover other European nations, including Germany.

But, as with other areas where Europeans lag behind, most notably intelligence, satellite surveillance, and missile-warning systems, catching up and replacing those capabilities will require time and significant investment.

A Europeanization of NATO "should have come before now," retired US Admiral James G. Foggo, who held senior posts in and linked to NATO, told the WSJ.

He said European members have many very professional officers and leaders.

"I think they have the capability. They've got some of the hardware" but need to invest and develop capabilities faster, Foggo said.