Forty-four years after the United Kingdom entered into an often tempestuous but not always loveless union with Europe, Prime Minister Theresa May will trigger formal divorce proceedings Wednesday.
She is to make a short statement to the House of Commons, then a letter will be hand-delivered to Donald Tusk, the European Council president, confirming that Britain is now seeking to leave the European Union.
No country has ever tried to do this before, and the procedure, set out in Article 50 of the Lisbon Treaty, is untested. It allows for a maximum two years of negotiations that, in their breadth and complexity, will be without precedent.
At the heart of the British position in these complex negotiations is a simple trade-off between sovereignty and prosperity.
In last year’s referendum campaign, May warned of the economic costs of exit. But since then she has changed her tune, interpreting the 52-48 percent vote by which the UK decided to leave Europe as a mandate to prioritize sovereignty over prosperity. She has rejected any suggestion that the UK could, even after it has left the EU, retain membership of the single market and its barrier-free trade. Instead, she has made it clear the UK is prepared to sacrifice this for stronger borders and immigration controls.
Across the negotiating table will sit EU leaders who are determined that the outcome of these divorce negotiations serve as a deterrent for any other country seeking to leave. With looming elections in France and Germany providing the next test for the resurgence of nationalist populism, they will resist anything that might encourage candidates and political parties to offer further departures from Europe.
The EU’s opening shot has been to demand an exit payment of 50 billion pounds ($62.8 billion) from the United Kingdom. The course seems set for a costly “hard Brexit,” involving either a new trade agreement between the UK and the EU or perhaps no deal at all, with all the uncertainty that would bring.
The United States, of course, has it own challenges just now, but the terms by which Britain leaves Europe matter to Americans too.
Economically, the UK is the fifth biggest economy in the world, and Europe remains the largest trading partner of the United States. So when British and European growth forecasts are downgraded because of Brexit, this hurts American exporters and American workers, too.
Diplomatically, Britain’s departure from the EU removes the United States’ closest diplomatic and military ally while also advancing Vladimir Putin’s ambition of a weak and divided Europe.
Already, the expectation of a hard Brexit has provided the pretext for the pro-independence nationalists who lead the Scottish government to demand another referendum on separation, just 30 months after the last one, which would call into question the very future of the UK.
But the most immediate impact on America of these negotiations may yet be political. On both sides of the Atlantic last year, a combination of economic anger, cultural anxiety, and political alienation produced a wave of populist sentiment that swept the UK out of Europe and Donald Trump into the White House.
At the time, voters backing Brexit or Trump were warned that a retreat into isolationism and protectionism would hurt them first and worst. But those issuing such warnings, along with all the mountains of evidence to back them up, were derided and dismissed in equal measure. Indeed, Leave campaigners and Trump echoed each other, declaring that the people have had enough of experts.
It may well be that, in this post-truth, post-trust era, populist politicians will continue to succeed in blaming immigrants and foreign workers for everything from the advance of automated production and digital technology to aging demographics.
But the British people who voted for the UK to leave the EU, just like many of those Americans who elected their 45th president, did so believing big restorative promises to take back control or “make America great again.” And polls show they thought they would be better off as a result.
This week, the campaign slogans of the Leave campaign will give way to the realities of negotiation in Brussels, just as they already have for President Trump on Pennsylvania Avenue.
After all, divorce can be an expensive, as well as a messy and painful, business.
Douglas Alexander is a fellow at the Harvard Kennedy School’s Belfer Center for Science and International Affairs and a former British minister for Europe.