The United Kingdom shocked many around the globe when it voted to leave the European Union (EU) on 24 June 2016. While the move will have political and economic effects on the EU, the departure risks undermining the current defense strategy in Europe. In the late 1990s, the French and British governments signed an agreement that would later form the European Security and Defense Policy (known today as the Common Security and Defense Policy, CSDP) of the EU. In 2003 the EU launched Operation Artemis in support of the United Nations peacekeeping mission in the Democratic Republic of the Congo. The deployment of EU soldiers proved successful, and in 2004 the leading EU members presented the concept for EU Battlegroups. These battlegroups would consist of 1,500 to 2,500 soldiers from militaries throughout the EU and could deploy to support peacekeeping and combat operations in both Europe and abroad. In 2005 the EU Battlegroups were formed.
Since its formation, the EU has organized 18 battlegroups. While many members of the EU are also part of the North Atlantic Treaty Organization (NATO), there are some member states that are not affiliated with NATO (most notably Finland and Sweden). The battlegroups are currently organized on a standby basis, with four battlegroups rotating throughout the year.
Of the EU member states, the United Kingdom has the second most powerful military (behind France). While the battlegroups are small, the loss of British forces to support an EU military operation can have profound effects. Currently, the UK leads the counter-piracy operation (Atalanta) off the Horn of Africa. While French and German warships are capable of supporting future anti-piracy operations, the loss of British support will put more strain on EU member’s navies to fill the gap.
In 2008, the members of Scandinavia and the Baltic states (Denmark is not part of the CSDP, and its position was filled by Ireland) formed the Nordic Battlegroup. With a resurgent Russia eying greater control of the Baltic, this battlegroup lacks the ability to halt Russian aggression should the need arise. As Finland and Sweden are not part of NATO, should Russia launch offensive operations against these two states, they would be entirely dependent upon the EU (although if Russia moved on the Baltic States or Norway, the NATO security agreement would bring all members to their defense). With the loss of the UK as a support, Finland and Sweden may choose to join NATO, a move that Russia has declared would result in backlash. Currently, Sweden and Finland have stated there is little desire to join NATO, but should Russia continue its aggressive behavior in the region, it may result in eventual membership into the powerful military alliance.