Europe cannot deter Russia alone as Trump rules out US troops for Ukraine

The arithmetic of European deterrence does not add up. When Donald Trump stood beside Keir Starmer at the White House and said the British have "incredible soldiers" who "can take care of themselves", he left the real question unanswered: could the United Kingdom, or Europe as a whole, actually fight Russia without American power? The private view of senior US officers is blunt. One very senior general, briefing in London recently, described the British Army as "too small". It now fields just over 70,000 regular troops, a figure that has shrunk steadily since the Cold War.

The arithmetic of deterrence

Numbers tell the story. According to the International Institute for Strategic Studies, Russia's military expenditure has risen 41% and now stands at the equivalent of 6.7% of GDP, higher, in purchasing power parity terms, than the combined defence spending of every European nation. The United Kingdom, by contrast, aims to reach 2.5% of GDP by 2027. That gap is not new, but it has widened sharply since 2022. Europe's collective effort is growing, yet the starting line was so far back that even rapid increases leave the continent short of the mass required for credible deterrence.

Volodymyr Zelensky has said Ukraine needs 100,000 to 200,000 international troops to prevent Russia from attacking again. Western officials, speaking on condition of anonymity, acknowledge that Europe cannot provide anything close to that figure. The working concept is a force of up to 30,000 troops, deployed not near the front lines in eastern Ukraine but at key sites, cities, ports, nuclear power stations, to provide what they call "reassurance". European jets and warships would monitor airspace and shipping lanes. It is a limited mission, deliberately so, because the capacity for anything larger does not exist.

What Europe can actually field

The 30,000 figure is aspirational. France is the only major European power that has publicly signalled willingness to contribute ground troops. Denmark, Sweden and the Baltic states are open to participation but want US security guarantees. Germany, Italy and Spain have so far said no. That leaves a coalition of the willing that is both small and militarily heterogeneous. The British Army's 70,000 regulars must also meet existing NATO commitments in Estonia and Poland, along with standing obligations elsewhere. France's army, larger at roughly 200,000 regulars, faces its own readiness and retention pressures. Neither country can sustain a division-sized deployment indefinitely without hollowing out other commitments.

The personnel shortfall is only the most visible gap. Europe also lacks the enablers that make modern military operations possible. Air-to-air refuelling tankers, strategic airlift, satellite surveillance, electronic warfare platforms, integrated command and control, these are overwhelmingly American assets. During NATO's 2011 Libya campaign, European nations nominally led the operation but depended on US refuelling and US targeting intelligence. The same dependencies persist. A European force in Ukraine would need American space-based reconnaissance to see Russian movements, American fighters on standby in Poland and Romania to deter Russian air attacks, and American logistics to keep supply lines open.

The missing enablers

One Western source put it plainly: the United States has supplied "the cream" of military aid to Ukraine, long-range missiles, advanced air defence systems, precision munitions. Europe has recently overtaken the US in the proportion of Western weapons delivered, but much of that equipment relies on American maintenance chains, targeting data and communications architecture. Without the US "backstop", a term officials use to describe a command and control element plus rapid-response air power, European leaders fear their troops would be exposed to Russian strikes with no credible means of retaliation or extraction.

Pete Hegseth, the US Defence Secretary, has been explicit: any international force in Ukraine will be neither a NATO force nor covered by Article 5. That means no automatic collective defence guarantee. Wes Streeting, the UK Health Secretary, suggested on Friday that Trump's verbal re-commitment to Article 5 might be enough to reassure allies. But Article 5 applies to NATO territory. Ukraine is not a NATO member. A verbal assurance from a president who has repeatedly questioned the alliance's value is not a treaty obligation. The distinction is not semantic; it is the difference between a deterrent that Russia must take seriously and a tripwire that Russia might calculate it can cut.

Libya's lesson

The 2011 Libya intervention is the template European planners cannot escape. British and French aircraft flew the majority of strike sorties, but they relied on US tankers to stay airborne and US intelligence to find targets. When the Obama administration stepped back, the operation's tempo slowed. The same pattern would repeat in Ukraine, only with higher stakes. Russia is a nuclear-armed peer adversary with integrated air defences, electronic warfare capabilities and a demonstrated willingness to escalate. A European reassurance force without US enablers would be operating at the edge of its technical and logistical limits, inside the range of Russian missiles, with no guaranteed extraction route.

The political fracture

Starmer convenes European leaders this weekend in London. The meeting will test whether warm words from Trump are enough to overcome the scepticism of capitals that have spent three years watching Washington's commitment waver. Germany's opposition is rooted in constitutional caution and a reluctance to be drawn into a conflict that could escalate to direct confrontation with Russia. Italy and Spain share that caution. Poland and the Baltic states, most exposed to Russian pressure, want the American guarantee precisely because they know Europe cannot provide it alone. France occupies a middle ground: willing to lead militarily but aware that its own forces are stretched.

The prime minister may still believe there is room for negotiation, that the US might yet agree to a backstop short of Article 5, perhaps a bilateral assurance, or a commitment to keep aircraft in theatre. But Trump's public position is settled: no American troops on the ground, economic presence only. The mining interests he mentioned are a commercial project, not a security guarantee. The gap between what Europe needs and what America will give remains unbridged.

What Starmer brought home

Starmer returned from Washington without a US security guarantee. He brought instead a presidential compliment about British soldiers and a question about whether they can take on Russia. The honest answer, acknowledged in private by the very allies who would have to fight, is no. Not alone. Not without the enablers only Washington possesses. Not with 70,000 regulars and a defence budget heading for 2.5% of GDP against an adversary spending 6.7%. The weekend's meeting will reveal whether European leaders are prepared to act on that reality, or whether they will deploy a force too small to deter, too exposed to survive, and hope the Americans change their minds.