Subregional defence collaborations provide the backbone of military cooperation in Europe and have become an integral part of the life of Europe’s armed forces. Subregional defence collaborations are the smaller bilateral and minilateral military projects that can function independently or as part of larger regional frameworks in Europe like the European Union (EU) and NATO. The relevance of subregional defence collaborations might be surprising at the first sight, as European regional level (NATO and EU) defence collaborations get much more media and academic attention than defence cooperation on the subregional level. For instance, when the French President, Emmanuel Macron called for a ‘true, European army’ at the centenary of the World War I Armistice in November 2018, or more recently when he emphasized that the EU needs to develop ‘strategic autonomy’, the news covered these topics extensively. However, when subregional level (bilateral, minilateral) defence collaborations are established, they receive less attention despite the fact that, currently, a web of hundreds of subregional military collaborations exist in Europe, many of them having been evolving for years or even decades.

If we look at some of the military initiatives of the last several years, we can see that many of them are smaller collaborations that are not necessarily part of European regional, NATO/ EU level cooperation. For instance, with the leadership of France, nine European countries – including the UK and Germany – created the European Intervention Initiative (EI2) in June 2018. In 2017 Sweden and Finland joined the British-led Joint Expeditionary Force (JEF) that now includes nine European countries. Furthermore, the armed forces of six Central European states started to cooperate against mass irregular migration in 2016. Bilaterally, while thousands of British and French troops exercise together regularly, in 2019 Germany and France signed agreements to collaborate on the development of several future defence systems. The UK Carrier Strike Group 2021, led by the HMS Queen Elizabeth aircraft carrier sailed to the Indo-Pacific region with the support of Dutch and US ships in 2021. In the same year, Greece and France agreed on a major package of bilateral military cooperation. Even many of NATO’s and the EU’s military projects are based on smaller subregional (bilateral, minilateral) groupings.