Even before the United Kingdom officially left the European Union in late January, Brexit had pushed the country into political convulsions for over three years. But as the dust settles, another long-feared ramification is coming into clearer view: Brexit could ultimately break up the United Kingdom itself.

The most attention has focused on Scotland, which voted against independence in 2014. The region has long been home to a vibrant independence movement, and a large majority of Scots opposed Brexit. In December, the ruling Scottish National Party formally requested authorization to hold another independence referendum. In reality, however, a breakup remains unlikely. Brexit may have alienated the Scots politically, but economically, it will bind them even closer to the United Kingdom—so much so that financial common sense will likely prevail over nationalist sentiments. If there is a real threat to British territorial integrity, it stems not from Scotland but from Northern Ireland, where the centrifugal forces of Brexit may prove too powerful to contain in the years ahead.

THE PRACTICAL SCOTS

The cause of Scottish independence has enjoyed an unlikely resurgence in the years since the region first held a referendum on the issue in 2014. Back then, the opponents of independence carried the day by more than ten percentage points. The defeat was supposed to have settled the question for at least a generation—until Brexit intervened. In 2016, the Scots voted by a large margin to stay in the EU, but they were overruled by their more numerous and Euroskeptical compatriots in England. Scotland’s pro-independence regional government has pointed to that fact to argue that Scotland was taken out of the EU against its expressed democratic will and has called for a rerun of the 2014 vote. Last year, tens of thousands marched in the streets of Glasgow in support of another independence referendum.

Many Scots understand that independence would come at a steep economic cost.

Despite appearances, however, it is not clear that Brexit has changed Scottish public opinion on independence all that much. Polls show some fluctuation—over the last year, for example, 15 polls have shown more support for staying in the United Kingdom, and three have shown more support for independence. It is a confusing picture, but overall, it resembles the situation in the run-up to the 2014 referendum. Moreover, although it is hard to say precisely why the 2014 referendum failed, it appears that many of those who opposed independence back then did so out of economic concern. These skeptics are unlikely to have come around since. Scotland remains deeply dependent on the wider British economy, and many Scots understand that independence would come at a steep economic cost.

The British treasury effectively subsidizes Scotland to the tune of about $17.1 billion a year, or a staggering $3,167 per person. About 60 percent of Scottish exports now go to the rest of the United Kingdom—four times as much as go to the EU. Far from an economic powerhouse in its own right, Scotland is, in the words of one commentator, turning into “a satellite regional economy” of the United Kingdom.

Brexit is likely to cement that peripheral status. A new trade deal between London and Brussels has yet to be struck, but it will undoubtedly introduce new barriers to trade, especially for services. Such barriers will make it even harder for Scotland’s service-oriented economy to get by on its own.

In 2014, such dependence on England would have mattered less: an independent Scotland could have become a member of the EU alongside the United Kingdom and continued to enjoy borderless access to its largest trading partner. Today, there is no such option. On the contrary, exiting the United Kingdom and joining the EU now would require Scotland to introduce border checks on the roads leading to England—not quite Hadrian’s Wall, perhaps, but still an enormous economic shock for two regions joined together by over 300 years of union. When states have disintegrated in the past—the Soviet Union and Yugoslavia, for example—the breakups have usually been economically disastrous. The EU, for its part, might not want to welcome into its ranks a weakened Scotland in need of massive subsidies.

An independent Scotland could, of course, choose to stay outside the EU and possibly even retain the British pound as its currency. But in that case, political independence would belie greater economic dependence on England. And the loss of political representation in Westminster would leave Scotland with even less control over its fate, ironically akin to the United Kingdom’s current dilemma in Brussels. Perhaps voting against one’s economic interests to achieve independence from distant bureaucrats captures the spirit of this age of nationalism. But Scotland has already proven once that it worships more practical gods. Most likely, that peculiarly Scottish faith will grow only stronger after Brexit.

THE COSMOPOLITAN IRISH

The real threat to the Union will arise farther west, from across the Irish Sea. Economically, Northern Ireland is starting from a position similar to Scotland’s. It is a heavily subsidized region with a service-oriented economy. Its most important export market—by leaps and bounds—is the rest of the United Kingdom, with the EU (including the Republic of Ireland) only a distant second. But if Brexit will pull Scotland’s economy closer into England’s orbit, it will push Northern Ireland’s in the opposite direction.

For years, negotiations over the terms of the United Kingdom’s exit from the EU were stuck on the question of the Irish border—how to avoid passport controls and customs checks between Northern Ireland and the Republic of Ireland if the former left the EU while the latter remained inside. The deal struck last year between London and Brussels solves this problem by essentially creating a border between Northern Ireland and the rest of the United Kingdom instead. Legally, Northern Ireland has now left the EU, but unlike the rest of the United Kingdom, it must still maintain a high degree of regulatory alignment with the EU.

If Brexit will pull Scotland closer into England’s orbit, it will push Northern Ireland in the opposite direction.

Given that arrangement, Northern Ireland is, over time, likely to expand its economic ties with the Republic of Ireland and with the EU at large and reduce its dependence on the United Kingdom. The magnitude of the realignment will depend on exactly how the Brexit deal works in practice, which is still a very open question. British Prime Minister Boris Johnson has insisted that the deal does not require customs checks between Northern Ireland and the rest of the United Kingdom, but the EU reads the same deal quite differently. And Johnson is nervous enough about Northern Ireland drifting away that he has suggested building a $25 billion bridge across the Irish Sea to better connect the region to the rest of the country.

Northern Irish unionists are anxious, too, and for good reason. Northern Ireland’s strange new status comes at a time when several trends are already reshaping the region’s traditional political and social fault lines. Northern Ireland has long been majority Protestant, but experts predict that the region could become majority Catholic as soon as next year. More than 20 years after the 1998 Good Friday Agreement ended the so-called Troubles and erased the border between the two parts of Ireland, younger generations on both sides are far less interested in the religious and nationalist divides that so inflamed their parents. Instead, they have mobilized in favor of “cosmopolitan” values, such as ending abortion restrictions and gay marriage. The shift has made its way into popular culture, too. Derry Girls, a new TV series set in 1990s Northern Ireland, chronicles the adventures of Catholic school girls who care less about religious divides than about finding cute Protestant boys to snog. In the eyes of the Irish writer Susan McKay, that carefree attitude has made the show’s heroines “the new emblems of Northern Ireland.”

For now, most polling of Northern Irish voters reveals little enthusiasm for leaving the United Kingdom. Still, support for independence is rising, albeit slowly. And unlike Scotland, Northern Ireland would not need to worry about being stranded outside the EU if it left the United Kingdom. That is because it has the option of unification with the Republic of Ireland, provided voters on both sides of the border agree in a referendum. In the republic, a majority already favor reunification, and in last month’s Irish general election, Sinn Fein—a party with a deep commitment to Irish unification—received the largest share of the vote. Unification would mean automatic EU membership for the north, with all the financial benefits that entails. Together, Ireland and the EU could easily subsidize the small province without major sacrifices. For now, that task falls to the United Kingdom, but the Good Friday Agreement requires the British government to grant Northern Ireland an independence referendum if there is a reason to believe a majority might vote in its favor. That day looks like it may come sooner than expected.

ENGLAND, ENGLAND

Neither Scotland’s nor Northern Ireland’s path is preordained. What is nearly certain, however, is that the independence movements in both regions will roil British politics for some time to come. The political reverberations of these movements, compounded by other post-Brexit domestic challenges, will keep the country self-absorbed and absent from the world stage for several more years. The ultimate impact of Brexit for the United Kingdom will come not from some sort of economic catastrophe that empties store shelves; it will come through national solipsism and the gradual relegation of a former hegemon to a decidedly provincial middle power.

This decline has already been the story of the last four years, and it will likely be the leitmotif of the United Kingdom’s coming trade deals with the EU and the United States. A smaller United Kingdom, finally confined to a single island, could represent the unfortunate but logical culmination of Brexit.