Brexit’s National-Security Impact: It’s More Than the Economy, Stupid

The United Kingdom will have a new prime minister at the end of this month. For the United States, the moment presents an opportunity to reflect on the primary challenge that the new British leader will face: Brexit. 

So far, U.S. policymakers appear to have seriously considered Brexit only from an economic perspective. In the run-up to and during Donald Trump’s visit to the United Kingdom last month, for example, U.S. officials and the President himself focused on the post-Brexit economic relationship between London and Washington. National Security Advisor John Bolton spoke of the President’s wish “to make a deal with Britain that will leave both of us better off.” President Trump tweeted about a “big trade deal” and spoke of the “tremendous potential with trade with the United States.” Even when another topic emerges in the American discussion, like the stability of the border between Northern Ireland and the Republic of Ireland, it is still tied to the economy or, more specifically, a potential free trade agreement. 

The economic relationship is crucial, but this narrow debate misses the wide-ranging consequences of the United Kingdom’s departure from the European Union. Brexit should matter for Washington within a broader political context, one that extends to defense, foreign, and security policy. As the United Kingdom reevaluates how it engages with the European Union and, therefore, Europe, so too should the United States. 

As one of the most prominent member states in the European Union, the United Kingdom’s leadership was – and, while it remains a member, continues to be – beneficial to the United States. Both countries maintain similar outlooks on the security environment, use of force, and, especially important for Washington, the centrality of NATO to European security. Defense officials across the Atlantic worry about the potential for duplication between the European Union and NATO and are keen to develop a mutually beneficial relationship between the two organizations. Because of this convergence, Washington has understood that London would ensure a strong link between NATO and new initiatives to strengthen defense cooperation among EU member states. 

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Once the United Kingdom leaves the European Union, however, it will no longer shape this debate from the inside. In fact, British officials will try to shape it from the outside, taking a greater interest in EU developments as the United Kingdom becomes a third country. For the immediate EU context, therefore, the United States will need to engage more closely with other countries that share similar views. Prime contenders include the Netherlands and the Nordic states, which have often cautioned that the European Union should not develop too strong a role in defense vis-à-vis NATO. Countries in Eastern Europe, such as Estonia and Poland, likewise view NATO, and the United States’ central role in it, as the bedrock of their security. 

It will not only be important for the United States to cultivate stronger partnerships within the European Union, but also to ensure the United Kingdom remains engaged in EU-NATO relations within the NATO framework. This is an area where British defense officials are keen to contribute. NATO has always been and will remain the center of British defense policy, irrespective of London’s EU membership. Yet it is unclear how NATO allies, some of whom are EU member states involved in the highly fraught Brexit negotiations, will react. Will EU member states recognize the longstanding and pragmatic role that the United Kingdom can continue to play? Or will these member states view this as an effort by the United Kingdom to influence the new EU defense initiatives through the backdoor? 

The answers to these questions will shape the United States’ approach to the EU-NATO relationship. If the United Kingdom’s role shrinks, the United States will lose an important ally in the debate and the gap could widen between NATO allies that want the European Union to shoulder more responsibility in defense, and those that are less enthusiastic. Although this debate takes on additional importance as EU member states move more quickly to develop new defense initiatives, itself a repercussion of Brexit, the situation is also precarious because of Washington’s own making. 

The Trump administration’s unorthodox linking of trade and security, as well as the surrounding rhetoric, damages its ability to play a constructive role in any discussion related to the European Union. In order to continue shaping this conversation through the EU-NATO relationship, therefore, Washington must not criticize the new EU defense initiatives simply because member states are developing them through the EU framework. The United States should recognize the potential for some of these efforts to strengthen EU member states’ defense capabilities and, therefore, the European pillar of NATO. This is where Washington, alongside London, should expend its political capital in the EU-NATO debate. 

If, as the President suggests, he wants to make the most of the “advantages of Brexit,” Washington should likewise manage the disadvantages. To continue engaging with the European Union and shaping the EU-NATO relationship, the United States must consider the repercussions of Brexit from more than just an economic point of view. Without broadening its perspective and changing tack on its approach to the European defense debate in particular, the Trump Administration will find itself increasingly isolated from Washington’s closest allies and partners. 

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