NATO 3.0: US Conventional Retrenchment and Nuclear Deterrence in Europe

At last week’s NATO Defence Ministerial, US Secretary of Defense Pete Hegseth announced Washington would be undertaking a six-month review of US posture in Europe. The review, according to Hegseth, will ensure Europe takes primary responsibility for its defence – including through reductions in US annual NATO dues should European allies fail to meet defence spending targets. The announcement further advances Trump’s clearly stated objective of reducing US contributions to Europe’s conventional defence. At the same time, Washington has been keen to draw a distinction between its conventional and nuclear contributions to European security. Yet, this division is a somewhat artificial one. A reduced US conventional presence, coupled with disparaging – and, at times, outright belligerent – US rhetoric is fundamentally at odds with American claims that US extended nuclear deterrence in Europe remains unaffected.

Extended Deterrence as a Consolation for Conventional Retrenchment

Even before Hegseth’s announcement of the ‘NATO 3.0 review’, the Trump Administration had made clear that the US will play a reduced role in European conventional defence going forward. While highlighting the continued importance of Europe to US security, the 2025 National Security Strategy noted that US policy will be to enable ‘Europe to stand on its own two feet . . . including by taking primary responsibility for its own defense’. The Pentagon had previously reportedly set 2027 as the deadline for Europe to assume majority responsibility for NATO’s conventional defence. Hegseth’s latest pronouncements of a six-month review appear to align with that timeline.

In early May, the US announced the planned withdrawal of 5,000 American troops from Germany and the cancellation of the expected deployment of a Multi-Domain Task Force (MDTF) long-range fires battalion, apparently in response to German criticism of Trump’s policy towards Iran. A few weeks later, the Pentagon confirmed it would be cancelling the rotational deployment of 4,000 US military personnel to Eastern Europe. Since then, Trump has said US personnel deployments to Europe would be reduced further still. More recently, the US told European allies it would be significantly reducing the number of fighter jets, maritime surveillance aircraft, aerial refuelling platforms, bombers, submarines and aircraft carriers allocated to NATO. As the Chinese threat to US interests in Asia continues to grow – and in light of depleting US weapons inventories as a result of Trump’s misadventure in the Middle East – any further US conventional withdrawals from Europe should not come as a surprise.

It is not just the withdrawal of US capabilities from Europe that has clearly signalled Washington’s determination to disengage from European security, but the way in which it has been carried out. The Trump Administration has brought a characteristically antagonistic and heavy-handed flare to its estrangement from Europe, adding insult to injury and – in doing so – adding political rupture to the reductions in deployed capabilities. Senior Trump officials have called out ‘European free-loading’ in private and made clear their disdain for European allies in public. In his speech at the Defence Ministerial, Hegseth accused NATO of having lost its way and called out allies for putting ‘America’s sons and daughters . . . at risk’ by not permitting the US to use European bases and ports for its war with Iran. Most damaging has been the outright belligerence Washington has displayed towards a number of NATO allies – namely, by not ruling out the use of military force to take control of Greenland and threatening to absorb Canada as the 51st state. The disdain with which the current US administration treats its European allies will not be lost on our adversaries.

Yet, despite – or perhaps, because of – the shift in US conventional posture and political rhetoric vis-à-vis Europe, the Trump Administration appears eager to reassure European allies that nothing has changed when it comes to the US’ extended nuclear deterrence. US officials repeatedly draw the distinction between American conventional posture and nuclear deterrence in Europe; while Washington expects European allies to take over primary responsibility on the former, the US will continue to take care of the latter. The Trump Administration’s earlier-mentioned announcements on draw-downs in conventional capabilities were quickly followed by a report in the Financial Times that the US had signalled a willingness to engage more NATO allies in hosting dual-capable aircraft (DCA). In February, Under Secretary of State for Arms Control and International Security Thomas DiNanno made repeated reference to the role the US nuclear deterrent plays in the security of US allies and the US’ readiness to adapt its extended deterrence posture as necessary to meet emerging security challenges. In the same month, Undersecretary of Defence Elbridge Colby also reportedly assured NATO allies the US nuclear umbrella remains intact over Europe.

Conventional and Nuclear: The Two Sides of the Deterrence Coin

US officials undoubtedly believe their own narrative – that extended nuclear deterrence can compensate for US conventional retrenchment from Europe. Unfortunately, effective extended deterrence does not lend itself to such a neat division of labour.

US conventional assets in Europe serve not only to directly bolster the defence of European allies but also underpin the credibility of extended deterrence. A US presence on the continent has historically helped couple US and European security interests and to provide some flexibility of response to Russian (and, before that, Soviet) aggression between capitulation and a strategic nuclear exchange. US troops in Europe act, inter alia, as a ‘tripwire,’ making credible US involvement in a war in Europe, including potential eventual US use of nuclear weapons. A large US ground presence is not, strictly speaking, necessary for an effective ‘tripwire’ and the withdrawal of US troops from Europe has been relatively limited thus far. Nevertheless, when coupled with the broader rhetoric coming out of Washington towards Europe, the posture shift makes much more challenging what has always been a difficult trick to pull off: to convince a nuclear armed adversary the US would be willing to risk a nuclear exchange in defence of Europe.

Even more detrimental to the credibility of US extended deterrence than the relatively limited US troop reductions is the roll-back in US-allocated advanced conventional systems – namely, the aforementioned cancelled deployment of the MDTF-2 long-range fires battalion and reductions in the allocation of various air capabilities and naval platforms to NATO. The battalion – which was expected to include SM-6, Tomahawk, and long-range hypersonic missiles (alongside the Typhon and Dark Eagle battery systems and other supporting assets) – would have made a much needed contribution to Europe’s deep precision strike (DPS) capabilities. Meanwhile, the reduction in US air and naval assets – including bombers and surveillance aircraft – undermine NATO’s already limited ISR (intelligence, surveillance and reconnaissance) and SEAD/DEAD (suppression and destruction of enemy air defence) capabilities, which rely primarily on US systems.

These capabilities are critical to the credibility of NATO’s conventional as well as nuclear deterrence posture. While not a solution to addressing Russia’s significant overmatch vis-à-vis NATO in theatre nuclear weapons, the role DPS can play in managing deterrence dynamics in Europe is well recognised. By credibly holding at risk critical Russian assets – including conventional forces and critical military supply chains – advanced conventional systems offer NATO meaningful escalation and signalling options short of nuclear strikes. In combination with a meaningful troop presence, advanced conventional capabilities allow NATO to both inflict and defend against sufficient damage so as to escalate a conflict (and pre-emptively signal the ability and willingness to do so) to a point where threat and use of NATO-committed US and UK nuclear weapons becomes credible.

There is also some indication Moscow is concerned over the counterforce threat advanced conventional systems pose to its strategic nuclear arsenal. Reinforcing the perception among Russian strategic planners that NATO could indeed inflict a damaging strike on its nuclear arsenal using conventional means, or that NATO’s conventional capabilities could supplement a strike with theatre nuclear forces, further bolsters the credibility of NATO’s in-theatre nuclear posture and complicates Russian decision-making. This, however, requires maintaining (and, indeed, improving) a robust NATO conventional posture, which should ideally be supplemented by additional investments into integrated air and missile defence (IAMD).

As such, US reduction of advanced conventional commitments to Europe not only sends political signals of decreased US resolve to intervene on behalf of Europe in case of Russian aggression, but also directly undermines deterrence dynamics in Europe by weakening rungs on NATO’s strategic escalation ladder. In the absence of these intermediate escalation options currently supplied by US capabilities, Russia may believe Europe would be forced to choose between attrition and eventual capitulation, or escalation to the use of UK or French strategic nuclear weapons. In the case of a limited Russian incursion into European territory, the risk is that the former may be seen as more credible than the latter.

Furthermore, little of what Trump Administration officials have said publicly explicitly or convincingly reiterates US extended deterrence commitments to Europe. DiNanno’s February speech makes no mention of Europe; China, however, is mentioned twenty-one times (twenty-three if one includes references to Beijing and the PLA). A recent speech by Elbridge Colby at the National War College, in which the Under Secretary outlined his vision for future US military strategy, comes up regularly in conversations with European government officials on US extended deterrence as confirmation the US views its alliances as a core aspect of effective deterrence. Colby does indeed stress the importance of a ‘binding strategy’ as a key element the US’ approach to deterrence – that is, convincing the adversary that escalating a conflict would ‘strengthen coalition cohesion’ and resolve. Yet, the first element of Colby’s deterrence strategy focuses on ‘denial defence’, as an alternative to a strategy of punishment or cost-imposition. The former, Colby argues, is best suited to deterrence in contexts where one’s political goals and the ability to credibly impose costs are limited. Especially when read with Colby’s long-standing emphasis on the need to prioritise Chinese threat in mind, the speech reads more like a confirmation of the Trump Administration’s deprioritisation of Europe than a source of consolation.

Seeing The World as It Is

A tendency towards optimism (or wishful thinking, depending on how one looks at it) in European capitals on the state of US extended nuclear deterrence in Europe is, perhaps, forgivable.. European states are not yet ready to fill a US-shaped hole in their security – whether in advanced conventional capabilities or nuclear deterrence. Though that is certainly not for a lack of effort or ambition.

Major increases in defence spending across Europe and initiatives towards the development of European alternatives to US advanced conventional capabilities have been documented extensively elsewhere. European states have also shown unprecedented initiative in rethinking the role nuclear weapons play in their security. With France’s ‘forward deterrence’ concept, the Élysée has gone about as far as politically feasible to signal an intent and a framework for closer nuclear coordination with non-nuclear allies. So far, the offer has been heartily taken up by eight non-nuclear European states, as well as the UK. The Franco-British Northwood Declaration and Nuclear Steering Group also open the door for closer nuclear cooperation between Europe’s two nuclear powers. Just last week, Finland’s Parliament overturned a long-standing ban on the stationing and transit of nuclear weapons on or through Finnish territory, which could allow for Finland to also join France’s ‘forward deterrence’ initiative. Following their joining of NATO, Finland and Sweden took an active role in NATO’s Operation STEADFAST NOOD nuclear exercise.

Yet, European states are quick to reiterate that none of these efforts can be a substitute for US extended deterrence in guaranteeing European security. It would be equally foolish to let ourselves be placated by assertions US extended deterrence in Europe is unaffected by US conventional retrenchment and accompanying political rhetoric. Even if the next occupant of the White House is a Europhilic Democrat, the damage to the credibility of US commitments to European security cannot be undone with one election; neither should the lessons. Europe must continue to prioritise increased long-term investments into non-US advanced conventional capabilities and a stronger conventional posture broadly. The UK and France must accept that their nuclear deterrents will have to play a larger role in European security going forward and should evaluate the sufficiency of their nuclear postures accordingly. While continuing to find ways to bind the US closer to Europe where possible, European capitals must also plan to deter and defend against Russian aggression alone if needed – through both capability investments and their own reviews of posture and planning – lest the cracks in the conventional foundation of US nuclear extended deterrence deepen further.

© RUSI, 2026.

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