NATO 3.0: from burden sharing to burden shifting and the Europeanisation of the Alliance
In 2026, changes in transatlantic relations ushered NATO into a period of restructuring. As part of the US concept of NATO 3.0, Washington announced a significant reduction in its military contribution to NATO’s defence plans for Europe in order to reallocate resources to the Western Hemisphere and the Indo-Pacific. At the same time, the US is reviewing its forces stationed in Europe, a process that could lead to a reduction in its military posture on the continent. This accelerates the shift launched at the 2025 NATO Summit in The Hague: from the goal of a more balanced division of responsibilities between Europe and the US (burden sharing), pursued between 2014 and 2024, to European NATO members assuming primary responsibility for conventional defence and deterrence (burden shifting).
The NATO 3.0 concept carries the risk of creating capability gaps in Europe’s defence that will be difficult to close. It will require closer military cooperation among NATO’s European members, a shift in how the Alliance plans and conducts operations with a smaller US role, and a faster increase in defence spending, combined with more effective use of Europe’s industrial and technological base. Any decision to relocate part of the US forces permanently stationed in Western Europe to Poland would strengthen deterrence on NATO’s eastern flank. However, it would not change the broader picture of a reduced US contribution to collective defence.
Shock therapy: a reduced US contribution to NATO defence plans
On 12 February, US Under Secretary of Defense for Policy Elbridge Colby presented the NATO 3.0 concept for transforming the Alliance at a meeting of NATO defence ministers. Under this concept, NATO must reverse the course it has followed for more than three decades under NATO 2.0, which was characterised by confidence in the liberal international order, cuts in defence capabilities and spending, and a focus on out-of-area operations. Instead, it must return to its Cold War foundations (NATO 1.0), with European Allies rebuilding their military capabilities. NATO 3.0 envisages a substantial reduction in the US forces and assets assigned to Europe’s defence, with European members of the Alliance assuming primary responsibility for conventional deterrence and defence, while the US nuclear umbrella remains in place. On 18 June, Secretary of Defense (War) Pete Hegseth confirmed at a subsequent meeting of NATO defence ministers that Allies had been informed of the scale of the planned reduction in the US contribution to the NATO Force Model.
The NATO 3.0 concept announced by the US Department of Defense (War) requires a significant acceleration of the Europeanisation of the Alliance’s conventional dimension, building on a process launched at last year’s NATO Summit in The Hague. In June 2025, Allies adopted more ambitious capability targets as part of the four-year NATO Defence Planning Process (NDPP; see ‘NATO summit in The Hague: Trump’s return and a two-component 5% of GDP on defence’). They also committed to providing the forces and capabilities required under the new NATO Force Model. Across all operational domains, the model comprises a pool of 800,000 troops at varying levels of readiness: more than 100,000 available within 10 days, around 200,000 within 30 days and at least 500,000 within 180 days. These forces are intended to implement NATO’s regional defence plans for the Alliance’s northern, eastern and southern flanks, which were approved at the 2023 NATO Summit in Vilnius.
According to NATO Secretary General Mark Rutte, the United States provided 44% of the Alliance’s military strength, as measured by its contribution to the NATO Force Model, in 2025. Under the agreements reached that year, this balance was expected to shift over the following decade, with Europe and Canada providing 70% of the required capabilities and the US the remaining 30%. This transition was to be supported by an increase in defence spending to 3.5% of GDP by 2035.
The transition was intended to take place gradually and in coordination with the European Allies. Current US plans envisage further reductions in the forces and assets assigned to Europe’s defence, including significant cuts to maritime and air capabilities, as well as to land units based in the United States and allocated to NATO defence plans. According to media reports, the reductions could affect surface ships and submarines, tactical and bomber aircraft, aerial refuelling aircraft and unmanned platforms.
Potential cuts in the US military presence in Europe
On 18 June, Secretary of Defense (War) Pete Hegseth also announced at the NATO ministerial meeting a review of the permanent and rotational US military presence in Europe, a process expected to take up to six months. The review will be carried out in cooperation with US European Command (EUCOM), Congress and NATO Allies. It will assess not only the number of troops stationed in Europe but also the terms of their deployment, particularly whether they allow US forces to operate freely from European bases. This reflects the decision by some Allies not to permit the use of their infrastructure and airspace during the US Operation Epic Fury against Iran.
According to the Special Inspector General report to Congress on Operation Atlantic Resolve, 80,253 US military and 6,499 civilian personnel were deployed in Europe during the first quarter of this year. The current number of US troops is estimated at around 75,000. This includes approximately 63,000 permanently stationed military personnel, of whom 38,000 are based in Germany and 10,000 in the United Kingdom, and around 12,000 rotational troops. After 2022, the United States temporarily increased its rotational presence in Europe by around 20,000 troops. Before 2022, these rotational deployments consisted of an Armored Brigade Combat Team (ABCT), a Combat Aviation Brigade (CAB) and a sustainment brigade. Following Russia’s invasion of Ukraine, the US also deployed a second ABCT and an Infantry Brigade Combat Team (IBCT) to NATO’s eastern flank on a rotational basis, among other forces. It also established a permanent forward headquarters of V Corps in Poland, reinforced the naval base at Rota in Spain and strengthened air defence capabilities in Germany. However, in October 2025, it announced the withdrawal of the rotational IBCT from Romania, among other locations. In May 2026, it also suspended ABCT rotations to Poland and Lithuania. As a result, the number of US Army formations in Europe returned to its pre-2022 level, that is, the level before Russia’s full-scale invasion of Ukraine.
The review has given rise to uncertainty because of contradictory signals and unannounced decisions from Washington. It remains unclear by how much the Department of Defense (War) will reduce the US military footprint in Europe, which also enables the United States to project military power into Africa and the Middle East. Any reduction below 76,000 military and civilian personnel for a period exceeding 45 days would require the Pentagon to assess its impact on US national security, conduct interagency consultations and consult the relevant congressional committees. Otherwise, part of the Department of Defense’s budget could be withheld (see ‘US defence budget for 2026: Congress approves continued support for Ukraine and a military presence in Europe’).
Europe outside its comfort zone
For the European Allies, the immediate priority is to ensure that the process is coordinated and predictable. The NATO Defence Planning Process (NDPP) offers the most appropriate framework for aligning the timetable for reductions in the US military contributions with European defence investment. This is likely to be one of the main issues at the upcoming NATO Summit in Ankara on 7–8 July. The aim should be to avoid capability gaps in NATO’s regional defence plans and thereby prevent any weakening of allied deterrence. Given the current US position, however, achieving this objective remains highly uncertain.
US decisions present the European NATO member states with a major challenge. They must continue implementing the capability targets agreed at the NATO Summit in The Hague while also replacing the capabilities that the Trump administration now intends to withdraw from NATO’s defence planning. This will require a rapid increase in the ambition of national defence policies, particularly in countries that continue to spend around 2% of GDP on defence.
The NATO 3.0 vision will require the European Allies to expand their land forces, increase the number of trained reservists available for wartime mobilisation and build up ammunition stockpiles. They will also need to strengthen logistics, air defence, long-range missilecapabilities, sixth-generation fighter aircraft, unmanned aerial systems of various types, transport and aerial refuelling aircraft, as well as electronic warfare and suppression of enemy air defences (SEAD) capabilities. In addition, they will need to enhance ISTAR capabilities (intelligence, surveillance, target acquisition and reconnaissance).
Prospects
NATO 3.0 does not mean that the United States is withdrawing from its Alliance commitments or ending its role in the defence of Europe and the deterrence of Russia. Under the version proposed by the second Trump administration, NATO remains the principal organisation for collective defence in the Euro-Atlantic area, but with a significantly different balance between European and US military responsibilities.
Alongside reducing its contribution to NATO’s defence planning and scaling back its military presence in Europe, the United States is also expected to reduce the number of its officers serving in NATO’s Command Structure and Force Structure. Even so, it intends to remain actively engaged in both. Following the latest changes, US generals will command the Alliance’s land (LANDCOM), maritime (MARCOM) and air (AIRCOM) component commands, while European officers will lead the Joint Force Commands in Norfolk (British), Brunssum (German/Polish) and Naples (Italian). However, proposals may continue to emerge in Washington for the United States to relinquish the post of Supreme Allied Commander Europe (SACEUR).
The reduction in US forces and assets assigned to the NATO Force Model is likely to be reflected in the Alliance’s next four-year NATO Defence Planning Process (NDPP), which is due to begin later this year. It is therefore reasonable to expect that the process will lead to the adoption of significantly more ambitious capability targets in 2029.
NATO 3.0 may lead the United States to place greater emphasis on military cooperation with Allies that make the strongest contributions in terms of defence spending and military capabilities. One indication of this was Under Secretary Colby’s June meeting in Bergen with representatives of Norway, Sweden, Finland, the Netherlands, Germany and Poland. According to Secretary Hegseth, these countries constitute “a small group of strong Allies”. The ongoing Polish-US discussions on establishing a permanent US base in Poland also reflect this approach.
A reduced US role in Europe’s conventional defence could also create an opportunity to discuss the strengthening of the US nuclear umbrella. This could include increasing the number of US tactical nuclear warheads deployed in Europe, expanding the means of delivering them, such as ground-based long-range missile systems, and extending nuclear sharing arrangements to additional countries (see ‘NATO’s nuclear deterrence: is it time for change?’).
Implementing the NATO 3.0 concept will require the European Allies and Canada to address three key shortfalls: personnel, capital and defence-industrial production capacity. In the case of expanding the size of their armed forces, many NATO members will face difficult decisions over reintroducing conscription, particularly in light of unfavourable demographic trends. The growing demand for non-US contributions to the NATO Force Model will also increase the need for additional sources of off-budget financing, as well as for greater productivity in Europe’s defence industry, including relocating the manufacturing of US defence systems to Europe.
