Political turmoil is growing on the island of Ireland. Each new development complicates the other. Here’s a quick summary:

• The minority government coalition in the Republic of Ireland is on the verge of collapse. The opposition Fianna Fail party is threatening to break the three-year deal it made with the Fine Gael party just 18 months ago. A dispute over a police whistleblower case is the surface reason, but don’t be fooled: this arranged marriage was rocky from the start. If  Fianna Fail walks, Irish voters may have to trudge to the polls before Christmas.
• As Reuters reports, this crisis comes three weeks ahead of a European Union summit in which the Irish government has an effective veto on whether Britain’s talks on leaving the bloc (Brexit) meet the Republic’s concerns about the future of the border with Northern Ireland. A weakened Irish government means less power at the bargaining table.
• In Northern Ireland, the power-sharing Assembly has been suspended since January, when the nationalist Sinn Fein withdrew from government over concerns about the role of Democratic Unionist Party leader Arlene Foster in a renewable energy scheme. The New York Times does a good job of piecing together the ensuing events. “This is a more profound crisis than we’ve had at other times in the last 20 years,” said a member of the Alliance Party, a smaller centrist group that does not identify as either nationalist or unionist.
• Complicating the border issues, Foster has written to the leaders of all 27 E.U. countries, telling them that Northern Ireland will not tolerate any difference in status between itself and the rest of the United Kingdom, after Brexit. She wants Northern Ireland to remain identified with the U.K. rather than any special arrangement with the Republic, as Sinn Fein wants. This reduces the chance of compromise on restoring the Assembly.
• Remember, earlier this year Foster also entered into coalition government with British PM Theresa May.  As The Guardian reports, Foster now accuses the Irish government of exploiting Brexit to attempt to unify Ireland.
• The ongoing Brexit negotiations, and what happens to the government in the Republic, will continue to impact Northern Ireland. Given the current difficulties, there may be calls to renegotiate the governing framework of the Good Friday Agreement, which reaches its 20th anniversary in April. Or political control may simply revert to London, a huge step backward. Next year also marks the 100th anniversary of the end of World War I and start of the Anglo-Irish War, which resulted in the island’s partition in 1921. Foster is right, in that talk of a referendum to reunify the island is only likely to increase.

Map of Ireland from the 1920s shows the partition of Northern Ireland and the Irish Free State, later the Republic of Ireland.