A possible weakening of NATO under the new US administration would have far-reaching implications for European security. European governments recognise the importance of transatlantic cooperation but differ in their expectations of Washington’s commitment and in their preferred responses if NATO’s role diminishes. Notably, calls for “European solutions” need not be synonymous with EU structures alone. Non-EU countries, such as the UK and Norway, remain pivotal partners in shaping any broader European security approach.

Heightened need for US reassurances

All governments emphasise the continuing need for a robust US strategic role in European defence. They seek clear signals – through troop presence, high-level commitments or sustained NATO exercises – that the US remains dedicated to collective defence. Overt expressions of support help mitigate uncertainty about the new administration’s potential pivot away from Europe.

Differing degrees of self-reliance

Across Europe, a shared belief is emerging that the region must become more prepared to handle some security challenges independently. But individual governments vary on how far they want to move in this direction. For some, the US remains the ultimate security guarantor. For others, the possibility of reduced US engagement is a prompt to strengthen Europe’s own capabilities and defence cooperation.

Yet, crucially, European cooperation goes beyond the EU alone. It may encompass regional and minilateral defence pacts, initiatives with non-EU countries, including the UK and Norway, or broader multinational frameworks. Essentially, the aim is to bolster Europe’s ability to address security needs, whether through dedicated European defence structures, closer regional coordination or combined efforts that bring in partners outside the EU framework.

Preference for Europeanisation or bilateralisation

If NATO becomes significantly weakened, governments will split broadly into two camps. However, many hold nuanced positions that borrow from both perspectives.

1. Europeanisation advocates

  • These governments view a diminishing US role as a compelling reason to deepen existing European defence cooperation and explore new frameworks.
  • They emphasise the need for broader European security solutions that include partners beyond the EU, ensuring the UK, Norway and other non-EU nations remain fully engaged.
  • Cooperation could manifest through standing operational agreements, joint training programs or large-scale exercises. Such collaborations are designed to strengthen Europe’s collective military capabilities without relying solely on US leadership.

2. Bilateralisation proponents

  • Other governments, especially those facing pronounced security risks, would lean more strongly on direct ties with Washington if NATO’s credibility erodes.
  • In their view, existing defence partnerships with the US offer immediate reassurance and often involve well-established channels for intelligence sharing, joint operations and logistical support.
  • While still supportive of some level of European cooperation, they see robust, country-to-country arrangements with the US as the most reliable hedge against a weakened alliance.

Strategic calculations and potential compromises

In reality, most European states will likely pursue both paths in parallel, continuing to build ties with Washington while investing in broader European collaboration. The exact balance will vary based on each country’s assessment of security threats, historical reliance on the US – and perceived feasibility of collective European defence outside NATO channels.

If the US administration adopts policies that substantially reduce NATO’s effectiveness, the debate around European solutions will intensify across EU and non-EU countries. While the EU may facilitate certain cooperative efforts, it cannot be the sole framework for all.

Broader partnerships with nations such as the UK and Norway remain essential to maintaining a robust, inclusive European pillar of defence. Ultimately, even if the transatlantic link weakens, Europe’s search for strategic autonomy will involve a variety of diplomatic and security arrangements that reflect each nation’s unique security concerns and alliance preferences.

About the author

Dr. Christian Mölling is Director of the Bertelsmann Stiftung’s Europe’s Future Program. He was previously Deputy Director of the Research Institute of the German Council on Foreign Relations (DGAP) and Head of the Center for Security and Defense.

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