Russia’s invasion of Ukraine in February 2022 overturned the strategic calculus behind Brexit. Then-Prime Minister Boris Johnson had promised to raise Britain’s sights beyond Europe—to the sunny uplands of closer trading and political relations with the United States and dynamic emerging markets in Asia. But the return of large-scale war to Europe has proved the adage that geography is destiny, bringing Britain’s strategic focus squarely back to its centuries-long priority of ensuring stability on the European continent.
Russia’s invasion of Ukraine in February 2022 overturned the strategic calculus behind Brexit. Then-Prime Minister Boris Johnson had promised to raise Britain’s sights beyond Europe—to the sunny uplands of closer trading and political relations with the United States and dynamic emerging markets in Asia. But the return of large-scale war to Europe has proved the adage that geography is destiny, bringing Britain’s strategic focus squarely back to its centuries-long priority of ensuring stability on the European continent.
Russian President Vladimir Putin’s brutal war does not merely threaten to erase Ukraine’s independence. Russian success—despite sincere European political commitment, military aid, and financial support to Ukraine—would shred the bonds that unite the European Union’s members. Combined with all the other pressures the EU already faces, this could not only collapse any emerging consensus on EU foreign policy and defense but also lead to the disintegration of the rules governing the bloc’s single market, border controls, and immigration.
This is not just a deep concern in Berlin, which wholeheartedly supports Ukraine over Russia. It is not just a concern in Paris, where French President Emmanuel Macron has described preventing Russia from winning the war as the “sine qua non” of European security and even is planning to deploy European troops to Ukraine. A potential Russian victory is also a profound concern in London.
A majority of Britons might have decided in 2016 to leave the EU. But that is not the same as wanting to see it implode. Even after Britain left the single market in 2021, the EU accounts for over half of imports and more than 40 percent of exports. A disintegrating European economy would thus carry severe repercussions for Britain. A loss of close coordination with the EU over migration, crime, terrorism, and political radicalism would have dangerous spillovers as well.
Moreover, if Europeans failed to uphold Ukraine’s sovereignty, many in the United States would conclude that Europe was a lost cause—and that it was time for the United States to turn its attention away. Washington might then sustain only a basic defensive deterrent in Europe and focus on the bigger strategic threat of a rising China, leaving Britain and its European neighbors to fend mainly for themselves in confronting Russia.
This long-term strategic view, shared by the major British political parties, is why Britain will remain one of Europe’s biggest military supporters of Ukraine. It also explains why London has been willing to give the Ukrainians weapons that the more cautious Biden administration had long withheld, such as long-range air-launched cruise missiles, which have been used against Russian targets to devastating effect.
It is also why, in January 2024, Britain was the first European country to sign a bilateral security agreement with Ukraine, which commits British military assistance for the next 10 years. Britain is also one of the most avid supporters of future NATO membership for Ukraine. And in the meantime, Britain is helping Ukraine’s forces and defense industry to become more interoperable with their NATO peers.
This view is why Britain now has 1,000 troops deployed continuously in Estonia, leading a multinational battlegroup as part of NATO’s Enhanced Forward Presence to deter future Russian aggression.
But like most countries in Europe, Britain is struggling to match resources with commitments. The size of its armed forces—around 130,000 regular, full-time forces across all services, as of April—has shrunk by almost one-third since 2000. Britain will need to help Europe develop more integrated approaches to security, combining each country’s specialties rather than continuing with today’s wasteful duplication. Britain’s defensive and offensive cyber-capabilities, as well as its world-leading electronic surveillance capabilities, will prove especially valuable.
Since Russia stopped most of its gas exports to Europe, Britain’s extensive regasification infrastructure and North Sea pipelines have enabled it to serve as a land bridge for liquefied natural gas exports from the United States and elsewhere to continental Europe. Britain is also woven into Europe’s increasingly important web of wind farms and subsea electricity interconnectors, which will need better protection from Russian sabotage. In January 2023, David Lammy, the Labour Party’s shadow foreign secretary, said the next Labour government would seek a formal security pact with the EU that would cement coordination across these areas, complementing NATO. With snap elections called for July 4, Labour will likely have that opportunity.
London’s return to focusing on European security, alongside its gentle tilt to the Indo-Pacific, aligns with Washington’s current policies. The question is what will happen after the November U.S. elections. Former U.S. President Donald Trump has made clear that the EU, which ran a surplus of more than $200 billion in its goods trade with the United States in 2023, will feel the full force of his retaliatory trade policy, of which Britain may be spared. While some in the Conservative Party may still favor a quixotic attempt to build a new bilateral partnership with the United States, don’t expect a Labour government—all but certain to be in power soon—to abandon the idea of a new strategic partnership with the EU.