A Saltire, Union Jack and E.U. flag outside the Scottish Parliament on March 13, 2017 in Edinburgh, Scotland. Scotland’s First Minister Nicola Sturgeon has confirmed she will ask for permission to hold a second Scottish independence referendum. (Photo by Jeff J Mitchell/Getty Images)

On Monday, Scottish National Party (SNP) leader Nicola Sturgeon delivered the political bombshell that Westminster elites were expecting, albeit much sooner than anticipated. She announced that she is introducing a vote to the Scottish Parliament for a second Scottish Independence referendum. Sturgeon anticipates holding the vote sometime between autumn 2018 and spring of 2019.  Here’s what you need to know.

The vote is tied to Brexit

The early timing of the referendum is deliberate. It is timed to occur in the middle of Britain’s negotiations to leave the European Union. Last June, 62 percent of Scots voted to remain in the European Union during the Brexit vote, in contrast to the 52 percent of voters who opted to leave from across the United Kingdom, which includes England, Scotland, Wales and Northern Ireland. The leave result allowed Sturgeon to re-open the question of Scottish independence, by saying that Britain taking Scotland out of the European Union against its will represented a “material change” since the 2014 independence referendum. E.U. membership has recently become the focal point for arguments in favor of Scottish independence.

Sturgeon claims that Theresa May’s Conservative government has been unresponsive to Scotland’s demands to retain its Single Market membership. Her desire to hold the referendum before Britain formally leaves the European Union stems from the hope that, by not yet exiting the European Union, Scotland would not have to reapply for membership.

The European Union has poured cold water on Scotland’s ambitions

Even though E.U. membership is the central rallying point for the SNP’s independence campaign, it is not clear that an independent Scotland can stay in. Within hours of Sturgeon’s speech, a spokesman for the European Commission noted that an independent Scotland would be subject to the “Barroso Doctrine.” Under this doctrine, states that come into existence when they secede from current E.U. countries have to reapply for membership status, as membership is politically nontransferable. The European Union delivered similar messages to Scotland during its 2014 Independence referendum, and snubbed Sturgeon and Scottish leaders when they appealed for a special regional deal with the trade block after the Brexit vote. The European Union’s reluctance to accommodate Scotland is a response to states like Spain which worries that its own secessionist movements in Catalonia and the Basque Country could use Scottish independence as a precedent.

However, Scottish membership could have benefits for Europe

This said, Scottish membership has possible attractions for the European Union, which is in the middle of a legitimacy crisis thanks to Brexit, migration, prolonged austerity, and challenges to liberal democracy in countries like Hungary and Poland.

The European Union perceives Britain’s current bargaining stance not only as unrealistic, but also diplomatically hostile. Theresa May has delayed triggering the E.U. Treaty process of withdrawal through invoking Article 50 of the E.U. Treaties, refused to guarantee residency rights to the 3 million E.U. citizens currently living in Britain, demanded that Britain maintain privileged access to European markets while barring free movement of people and not being subject to the European Union’s top court, and threatened to walk away from Brexit negotiations if the European Union offered a “bad deal” (which would automatically mean that Britain had no better access to the Single Market than any other member of the World Trade Organization).

Supporting and accommodating an independent Scotland would provide the ultimate rebuke to May for Brexit. It would signify that leaving the European Union has far greater costs (the end of the nation-state) than those tied to losing access to European markets. It’s hard to imagine an outcome worse for May’s “Global Britain” than the United Kingdom’s formal dissolution. Scottish independence would also bolster unification ambitions for Northern Irish nationalists.

Furthermore, an independent Scotland would provide the European Union with a sympathetic ally in its time of political need.  It’s not only Britain that is disillusioned with the European Union. Poor handling of the European debt crisis has increased euro-skepticism in states that were previously highly pro-E. U. (Greece, Spain and Italy). The strains of the refugee crisis have heightened tensions between the EU’s East and West. Donald Trump’s erratic opposition to the European Union has not helped either.

Sturgeon’s SNP party, in contrast, is a highly vocal defender of the virtues of the European Union and unfettered access to the Single Market.  Moreover, by recently distancing itself from fellow separatists in the European Parliament, the SNP has demonstrated its desire to accommodate the concerns of other E.U. member-states (namely Spain), rather than antagonizing the European Union as the British Conservatives have done during Brexit and before it (in 2009, David Cameron withdrew the Conservatives from the main right-of-center grouping in the European Parliament, allying with more right-wing fringes).

The Scottish referendum may shape the negotiations

As Brexit negotiations move forward, the European Union may benefit from a Scottish referendum if it happens in Sturgeon’s suggested time frame. Theresa May and hard Brexit Conservatives say that they are willing to bear the economic costs of a ‘hard Brexit,’ in which Britain significantly dissociates itself from the European Union. However, their enthusiasm may be dampened by a brewing constitutional crisis, especially if the European Union starts sending encouraging signals to Scotland. While allowing a seceding region of a member-state to retain its membership would be unprecedented, it wouldn’t be the first time the E.U. accommodated varying degrees of membership status within individual sovereigns. Denmark remains an E.U. member despite the fact that Greenland, which is part of Denmark, opted to leave the bloc in 1985.

Sturgeon’s announcement delayed May’s decision to trigger Article 50 this week. This demonstrates that Scottish separatism is a cause of grave concern to Conservative euroskeptics.  If the European Union provides continuing membership to an independent Scotland, or supports a unique Scottish relationship with the European Union, it could potentially disrupt Britain’s constitutional relations, with serious political consequences for the government that ‘lost’ Scotland. This would be playing true hardball — if the European Union believes that Britain has been making extreme threats to win concessions during negotiations, it might, over time, come to see the attractions of doing the same.

Alison Johnston is an assistant professor of political science at Oregon State University. Her work focuses on European integration, E.U. politics and the domestic causes of the European debt crises.