Northern Ireland receives millions of pounds in farming, fishing and structural subsidies from the European Union, as well as money to preserve the Good Friday peace deal. In 2015, the European Union sent Northern Ireland 320 million pounds ($402 million) in subsidies and around 50 million pounds in peace funds. This money will no longer be available when the United Kingdom leaves the bloc, meaning that the British government would probably need to seek ways to replace it. The United Kingdom's membership in the European Union also allows Northern Ireland to keep its border with the Republic of Ireland open, contributing to the pacification of the island. After Brexit, there is a chance that some kind of border controls will have to be introduced. The letter delivered by the British government formally triggering the Brexit included Northern Ireland as one of the main topics for its upcoming negotiations. In the meantime, an internal EU document with draft guidelines for the bloc's talks with the United Kingdom suggests that "flexible and imaginative solutions" will have to be found to preserve the Good Friday Agreement.

Northern Ireland is going through a phase of political turbulence. The Good Friday deal, finalized in 1998, brought decades of sectarian violence to an end. But the political system it created, in which unionist and nationalist forces share power, has also frequently led to inefficient governments. Frictions between the two largest parties, the Democratic Unionist Party (DUP) and the nationalist Sinn Fein, precipitated the fall of the government in early 2017. In the snap elections that followed, Sinn Fein performed strongly, potentially indicating a surge in nationalist sentiments in Northern Ireland.

When the period allotted to form a government expired March 27 without success, the British government gave the parties until April 18 to reach agreement. On the surface, the DUP and Sinn Fein are divided by issues such as a nationalist proposal to give Irish language official status in Northern Ireland. But Sinn Fein believes that its strong electoral performance and Brexit have improved Northern Ireland's chances of unification with the Republic of Ireland. According to the Good Friday Agreement, a unification referendum can happen if a majority of voters in Northern Ireland express their wish for it. A survey taken in late 2016, put support for a unification referendum at around 40 percent.

If the parties cannot form a government, the British government is legally authorized to take direct control of Northern Ireland, but this is something that May wants to avoid. Even if there is an agreement to temporarily unblock the current stalemate, the Good Friday Agreement is showing signs of exhaustion, and the Brexit process will create frictions between unionists and nationalists, which means that political instability will probably continue.

In late February, the Republic of Ireland's prime minister, Enda Kenny, said that the final Brexit agreement with the European Union should include a provision to let Northern Ireland automatically become a member of the European Union if it unifies with the republic. Then in early March, Fianna Fail, the Republic's main opposition party, announced that it is working on a plan to prepare the north and the south for unification. While both parties have said that unification is still a distant possibility, these moves show the extent to which Brexit will reopen discussions about the territorial and political future of the British Isles.

Seeking Advantage in Wales

Support for Welsh independence is low, with polls persistently showing less than 10 percent of the population in favor. Like their English peers, a majority of Welsh voters supported leaving the European Union in the 2016 referendum. But while independence is not an immediate threat, Welsh leaders are looking for ways to benefit from the Brexit process. First Minister Carwyn Jones recently warned that regulations on issues that affect Wales such as agriculture, which is currently an EU prerogative, should be transferred to Cardiff instead of London after Brexit.

Wales also expects to gain from whatever concessions London makes to Scotland. In the months leading to the Scottish independence referendum of 2015, for example, London promised to grant Scotland additional powers over taxes, welfare benefits and energy. In the coming months, London may offer new sweeteners to Scotland to appease secessionist sentiments. This will open the door for Wales to make its own demands. While the Welsh issue will not be nearly as pressing as the Scottish or Northern Irish questions, it will create yet another headache for May's Cabinet.

A Tussle Over Gibraltar

In Gibraltar, 96 percent of residents voted to remain in the European Union. It is a British Overseas Territory that participates in the EU's free movement of people, services and capital; but not in the free movement of goods or in programs such as the Common Agricultural Policy. The main activities of Gibraltar's services-based economy include financial services, tourism and online gaming. Roughly half of its workforce consists of EU citizens (mostly Spanish) who are daily commuters, and most tourists arrive to the territory by land. To make things more complicated, Gibraltar's territory is claimed by Spain.

Brexit poses two risks for Gibraltar. The government is worried that Gibraltar's exports will no longer have tariff-free access to the EU single market, especially because a free trade agreement will be easier to negotiate for goods than for services. It is also concerned about Spain unilaterally closing the border and isolating the territory (since the United Kingdom is not a member of the passport-free Schengen Agreement, identity checks already take place at the border). The government of Gibraltar excluded the possibility of leaving the United Kingdom and joining Spain, but it recently held talks with Scotland to jointly seek ways to remain in the single market.

According to a draft of EU guidelines for the Brexit talks, the Brexit deal would not apply to Gibraltar without a separate agreement between the United Kingdom and Spain. But Madrid will probably not pressure London too much over Gibraltar, at least during the early stages of the Brexit negotiations. Madrid and London will be interested in reaching a deal to protect the rights of the 300,000 British citizens who live in Spain and the 200,000 Spaniards who live in the United Kingdom, as well as to preserve their strong bilateral trade and investment ties. In the future, however, Madrid will gain some leverage it could use to negotiate the status of Gibraltar. To win approval for a free trade agreement would require the unanimous support from all EU members, which would give Spain veto power over the final deal.

Legal and Political Issues

The Scottish government has said it will seek to remain in the single market, either through independence or by a special agreement with the European Union as a member of the United Kingdom. Should Scotland become independent, it would not automatically become an EU member. The Scottish government has suggested that if it does become independent, while it applies for EU membership it could in the meantime become a member of the European Free Trade Association, a club of non-EU countries (including Iceland, Liechtenstein, Norway and Switzerland) that participate in the single market. Should Scotland remain in the United Kingdom, Scottish authorities have suggested emulating Denmark, where parts of its territory are in the EU, while others (such as Greenland and the Faroe Islands) are not.

In Northern Ireland's case, secession from the UK would almost certainly lead to EU membership. Northern Ireland would join the Republic of Ireland, which already is a member of the EU. A similar situation occurred in 1990 after German reunification.