Uncertainty surrounding Merkel's fate is not good for Ireland in Brexit talks
A fourth consecutive term as German Chancellor was always going to be a tough challenge for Angela Merkel - but she has still been deemed favourite to pull it off. A major terror attack in Germany - linked rightly or wrongly in the popular view to immigrants - will make her task all the more difficult.
Elections in four key EU founder member states, all of which have big implications for Ireland, loom in 2017. But the federal elections due in Germany had looked least bothersome, as Ms Merkel looked most likely to hang on as a beacon of liberal politics and EU stability.
That would be good news for Ireland as Enda Kenny's Government has invested in cultivating a relationship which might help through tricky Brexit talks.
Recent experiences have shown that the migration issue was Ms Merkel's political Achilles heel. Despite initial support for her mix of courage and political pragmatism, she met with a considerable backlash in the wake of 890,000 registered asylum applications in 2015.
Since September, the chancellor has noticeably dropped her "we will manage" mantra on the issue. She has been busy assuring allies that the 2015 level of migrant influx will not be repeated, though 2016 numbers are expected to top 300,000. In her first comments following the Berlin Christmas market outrage, she tried to dispel fear, insisting the country would continue to live "free, together and open".
But Ms Merkel, now aged 62 and in power since 2005, also acknowledged problems should the incident be definitively linked to culprits who were seeking protection from the German state.
The far-right Alternative for Germany party (AfD) lost no time as one of their politicians dubbed the 12 who died in Berlin as "Merkel's dead". Others in the party were only marginally less brutal. "The environment in which such acts can spread was carelessly and systematically imported over the past one-and-a-half years. It was not an isolated incident and it won't be the last," AfD co-chairman Frauke Petry said.
That opportunistic AfD attack was to be expected. It was quickly countered by members of Merkel's CDU party who said the AfD were "doing the work of [Isil]" by stoking fear and division.
But it is the knock-on effect within her own party which will be watched with interest. The Christian Democrat CDU's allies in Bavaria, known as the CSU, have been at odds with Ms Merkel over immigration and this incident has added to that tension.
The Bavarian CSU leader, Horst Seehofer, publicly sounded a warning note. "We owe it to the victims, their loved ones and all German people to rethink and overhaul our migration and security policies," he said.
Facing into Brexit talks from next April, the last thing Ireland needs is instability in Germany adding to doubts about the country's commitment to the EU. Elections in Netherlands next March, in France in late April and early May, and in Italy probably also next year, will usher in a period of particular uncertainty.
The opening phase of Brexit talks will be noisy and negative. Chancellor Merkel's presence is required.