The ballistic missile submarine HMS 'Vanguard' alongside the 'Type 45' destroyer HMS 'Dragon' in 2010. Royal Navy photo
It's not every day one of Europe's largest economies votes to pull itself out of the European Union, the British prime minister announces his resignation and serious questions erupt regarding the future of the Western political order.
But fortunately for NATO and the British military, it's not time to panic … yet. The military implications of Brexit will not set in overnight, and Britain has a backup plan.
However, there could be profound consequences for the alliance and the British military over the long term — some of them negative.
For one, NATO is responsible for Europe's collective defense, not the European Union. The United Kingdom will remain one of Europe's largest economies and will continue to wield outsized global influence due to its permanent seat on the U.N. Security Council.
Nor does leaving preclude Britain from participating in the E.U.'s military missions, such as chasing pirates off the Horn of Africa.
The British economy has tanked, but Britain will survive. The actual process of withdrawing from the European Union is also exacerbated by the entangling of European and British case law, which will take years to sort out.
Parliament must ratify the referendum for it go into force — and what remains of the British-European relationship years from now is a mystery. But there's no doubt that Brexit (if it happens) could have major consequences for British foreign and military policy.
A June briefing paper from the Royal United Services Institute, a London-based defense and security research organization, described a a possible withdrawal from the European Union as "significant a shift in national strategy as the country's decision in the late 1960s to withdraw from bases East of Suez."
That's a big, sweeping and once-in-a-generation shift.
It was evident at the time. In the late 1960s and early 1970s, the United Kingdom withdrew its military from East Asia and the Middle East to focus on countering the Soviet army in Europe. This period coincided with the Troubles in Northern Ireland, where British Army troops deployed beginning in 1969.
Britain joined the European Union's predecessor organization in 1973. In short, Britain's growing military ties with Europe were inexorably bound with growing economic and political ties.
Those ties shaped the British military.
The Royal Air Force scrapped its long-range Avro Vulcan strike bomber, which wasn't needed to defend the homeland from a Soviet invasion. Britain put off building new aircraft carriers, but developed Trafalgar-class attack submarines to hunt Russian subs in the North Atlantic.
Britain's Tornado fighter jets are also a product of the 1970s, built by a German-Italian-British consortium and designed specifically to fight Soviet forces in Europe.
The Falklands War served as a brief interlude in 1982. But beginning in the 1990s, Britain would shift to a more internationalist posture, fighting wars in Iraq and later Afghanistan, where Britain still keeps 450 troops in an advisory role.
Today, British warplanes and advisers are involved in the war with the Islamic State in Iraq and Syria. The U.K. military is increasingly involved in Africa.
A Royal Air Force Typhoon in 2012. Peter Gronemann/Flickr photo
In short, the British military is less focused on Europe, and is more globalist, than it was during the Cold War.
So in an irony for Brexit's most isolationist supporters, one possibility is that a post-E.U. Britain might increase its role in NATO to make up for its declining influence in European capitals. Especially now that European governments worry about Russia's military build-up.
"The U.K. might find that the extent of its commitment to European defense would be one of its few bargaining chips as it entered a period of tough negotiations on the terms of its future economic engagement with its E.U. neighbors," Malcom Chalmers of the Royal United Services Institute wrote.
The outcomes of the 2016 NATO summit in Warsaw in July are likely to further constrain the U.K.'s room for maneuver, committing the U.K. to invest in deployments and capabilities whose main role will be to contribute to deterrence of Russia. New crises in Europe and its neighborhood (for example in the Balkans or Africa) could also increase immediate demands on U.K. capabilities, especially in cases where the U.S. makes it clear that it expects Europe to take the lead.
In these circumstances, as Europe's most capable military power, the U.K. could not easily stand aside from the European consensus without significant risk to its reputation as a reliable NATO partner.
Nor can a resurgence of security concerns closer to home be ruled out.