Moving Beyond “Berlin Plus”

As Russian tanks rolled into Ukraine in 2022, Europe was reminded that peace on this continent could no longer be taken for granted. Russian production figures for main battle tanks have roughly tripled over the last three years. This reality highlights the essential role of a robust EU–NATO partnership in addressing the escalating military threats in the current security environment. As a strategic partnership between EU and NATO is considered crucial to maintaining security and stability in the Euro-Atlantic area, the legal relationship between these two organizations is of particular importance. To serve the goal of protecting and deterring, the question arises how then might it be organized in the future? If the legal regulation of interstate relations is already complex, this is even more true for legal relations between international organizations.

With the increased US interest in breaking away from European security structures, and the still present idea of a “dormant NATO”, the need for the EU to develop autonomous military capabilities has become more acute than ever. As the President of the EU Commission von der Leyen emphasized in a statement on 30 September 2025, there is “a single set of forces, assigned to different missions – NATO, EU, UN or Coalitions of the Willing”. Some influential German political scientists have recently suggested (“Sicherheitshalber” at 01:18h), a way forward to address US decoupling efforts could be reviving the little used 2002 Berlin Plus Agreement. This agreement enables limited use of NATO  structures by EU-member states and sharing intelligence. Although it seems questionable that European armed forces can act under this arrangement when NATO as a whole is not involved.

Legal Nature of the Berlin Plus Agreement

The envisioned shared use of units and facilities may result in two organizations competing for the same resources. In this regard the agreement has never been tested. As NATO must first decline to act for its assets to be released for use by the EU this rule amounts to a “right of first refusal”. In consequence, this places respective EU-led operations under the caveat of approval by non-EU-members. Turkey for example did delay the use of NATO assets for EU-led Operation Concordia in 2003 for over five months. For several reasons, namely lack of a specific treaty-making capacity of the EU at that time, its half-secret nature and its title as a “Declaration”, the Berlin Plus Agreement does not constitute a legally binding treaty under international law. The parties also lacked the will to be legally bound. It must rather be considered a non-binding political agreement. Consequently, none of NATO’s assets or planning capabilities are “promised” to the EU in a legal sense, regardless of equal goals.

Content of the Berlin Plus Agreement

“Berlin Plus” actually is a collective term for a comprehensive package of agreements between NATO and the EU, which form the legal basis for the relationship between the two organizations. They were a direct outcome of the 1999 NATO Washington Summit’s commitment to strengthening the European Security and Defence Identity (ESDI) and providing the EU with a greater capacity to act militarily independently.

At the time of the Berlin Plus Agreement, US Secretary of State Madeleine Albright’s 1998 dictum of “no decoupling, no duplication and no discrimination” as repeated caveats of “three Ds” on European defence structures besides NATO, was still resonating. The collapse of Yugoslavia had dramatically demonstrated Europe’s inability to address security issues without US-involvement, even when concerned with issues on its own continent. Hence the Berlin Plus Agreement could also be regarded at the time as the abandonment of any European ambitions to create truly autonomous defence capabilities.

On 16 November 2002 EU and NATO announced the conclusion of an agreement in the Joint Declaration on European Security and Defence Policy (ESDP) which allows the EU to draw on NATO military assets (42 ILM 242 (2003)). A document to that effect had been signed by the then NATO Secretary-General George Robertson and the EU’s High Representative for Common Foreign and Security Policy Javier Solana. The agreement is based on the principle of “separable, but not separate” forces.  This principle means that the same national military units may be employed in either EU-led or NATO-led missions, while remaining integral to NATO’s overall force structure and commitments.

One part of the agreement on assured access to NATO’s planning capabilities was set out in a  classified decision of the North Atlantic Council (NAC). Discussion of its content can thus only be partially  based on a subsequent NATO press statement (NATO Press Release(2002)142 of 16 December 2002). From this, is remarkable that  it foresaw the appointment of the Deputy Supreme Allied Commander Europe (DSACEUR), to command EU operations, using NATO resources. Since its creation in 1951, this office has always been held by a European officer, usually by a British officer with Field Marshal Montgomery as the first office holder. (From 1978 to 1993 there were two DSACEURs, one British and one German.) Furthermore, the EU was granted assured access to NATO’s planning capabilities and collective assets, such as communication units and a headquarter for its own crisis management operations. An “Agreement between the European Union and the North Atlantic Treaty Organisation on the Security of Information” enabling an exchange of classified information under mutual protection rules, was added to this on 24 March 2003.

The Scarce Practice under the Berlin Plus Agreement

For command arrangements and operational planning support, the Berlin Plus Agreement enables NATO to support EU-led operations in which not all NATO member states are engaged. To date, only two rather small EU military operations have been conducted on this basis: From March to December 2003 the EU Operation “Concordia” took over the NATO peacekeeping operation “Allied Harmony” (initially Operation “Amber Fox”) with a manpower of 350, monitoring the implementation of the peace plan for Macedonia, based on UN Security Council Resolution 1371 (2001). The only ongoing operation under this agreement is EUFOR Althea. It took over from NATO Stabilization Force (SFOR) in 2004, based on UN Security Council Resolution 1575 (2004). The current strength of EUFOR Althea is about 600 soldiers and its mandate is supporting Bosnia and Herzegovina’s authorities in maintaining security. The operation uses NATO’s Supreme Headquarters Allied Powers Europe (SHAPE) as the EU Operational HQ (OHQ).

EU-NATO Goals and Partnership Overlap, Enough Guarantee to Secure Cooperation?

NATO and EU have legally fixed coinciding goals: NATO is committed to safeguarding  “the freedom, common heritage and civilisation of their peoples, founded on the principles of democracy, individual liberty and the rule of law“(Preambulatory Clause NATO Treaty). The EU is “founded on the values of respect for human dignity, freedom, democracy, equality, the rule of law and respect for human rights“ (Art. 2 Treaty on European Union) and aims “to promote peace, its values and the well-being of its peoples“(Art. 3 (1) Treaty on European Union). Membership overlaps between the EU and NATO with only four EU member exceptions  (Austria, Cyprus, Ireland, and Malta) as non-NATO members.   However, they are considered natural partners and their cooperation is regarded as a necessity. Yet, Six European states (Albania, Iceland, North Macedonia, Norway, Turkey and the UK), as well as the two crucial North American states Canada and the USA are not members of the EU.

This similarity of goals and membership overlap does not mean that the relationship between the two is free of tension. Indeed EU-NATO cooperation has proven difficult. The question was even raised whether their cooperation could survive a second Trump administration.  Already before President Trump’s first election in 2016, there were warnings that this would endanger European security. Regardless of changes in government, the practice of EU-NATO cooperation has expanded significantly in recent years. Both are increasingly coordinating shared strategic priorities, building on three joint declarations (2016, 2018 and 2023). In the most recent joint declaration, adopted on 10 January 2023, the EU and NATO equally condemned Russia’s war of aggression against Ukraine and support Ukraine’s sovereignty, territorial integrity, and right to self-defence.

Developing Operational EU-NATO-Relations Further?

In their confirmation hearings before the European Parliament in 2024, the defence and foreign affairs commissioners envisioned a complementary, rather than competitive, relationship between EU and NATO. They declared developing capabilities required for the implementation of NATO military deterrence and defence plans a policy goal of the EU. However, some persistent challenges remain: non-member states in both organizations still limit activities like sharing classified information. Additionally, some states prefer relying on NATO or bilateral ties with the US over enhancing joint EU defence efforts. EU member states have different views on the scope and applicability EU’s mutual defence clause (Article 42(7) TEU). But is the Berlin Plus Agreement fit to address the EU’s current situation?

The Berlin Plus Agreement must be considered to be out of date in the current strategic situation. It was adopted at a time when both organisations were involved in crisis management missions and “out of area” peacekeeping operations. The intention behind the Berlin Plus Agreement was to prevent unnecessary duplication of resources for ​​crisis management. It aimed at institutionalising a cooperation between EU and NATO that was virtually non-existent during the Cold War. It also was designed to re-legitimise NATO´s relevance, whereas today hardly anybody questions its relevance anymore. At the time of its conclusion, the creation of truly autonomous European defence structures was inconceivable to staunch Atlanticist Member States, like the UK and Denmark.

Several practical objections speak against further developing the existing structure: Since Brexit in 2020, the usual British DSACEUR is no longer an EU citizen, which renders the construction partially moot. Since Cyprus joined the EU in 2004, Turkey and Cyprus could veto each other’s position on activating the mechanism in NATO or EU respectively. Subsequently, due to the complexity of the mechanism, national headquarters were used to conduct EU missions (e.g. 2006 the Bundeswehr Operations Command in Potsdam for EUFOR RD Congo). Foremost, the mechanism has not been used in the context of national and alliance defence. It was never intended to serve this purpose.

Conclusion

Berlin Plus served a narrowly defined purpose at the time it was concluded. The arrangements created for “out of area” missions cannot be boosted to a structure needed for continental defence purposes as currently required. NATO’s integrated command structure, created in 1951, is ultimately managed by the USA. Given the extent to which NATO structures are supported by US personnel, such a construction seems unrealistic. European autonomy will not be achievable without -at least- a gradual decoupling and duplication of assets. With changing US priorities, European states must accept that the new guiding principle cannot be “separable but not separate” forces but “genuinely separable” forces.