The war between Russia and Ukraine still rages on after three and a half years. More than one and a half million soldiers have died or been wounded. There are nearly daily attacks on Ukrainian cities. Millions of people have migrated, especially from and within Ukraine.The economies in both countries, but also in Europe and beyond have suffered substantially. The West has spent $300 billion on economic and military support for Ukraine. Other major threats, such as global warming, have disappeared from the priority list.
Just like the war that began in 1914 and ended four years later and also the Second World War that ended in five years,the Russia–Ukraine war will also end at some point, hopefully in the not-too-distant future. Since 2025 there have been diplomatic efforts to stop the war, with the United States as mediator. But little thought seems to be going in to the post-war period. This paper tries to fill this gap by asking how the European security order could be imagined once the fighting has stopped.
More particularly, it might be asked which (regional) international organisations could and should play a role in filling the void after the war. International organisations give rise to order and stability as they require cooperation on a daily basis. Another advantage of institutions (and international regimes in general) is that they do not immediately fall apart once a problem arises. Due to long-term cooperation, there is a certain level of respect and trust between the member states that can act as guardrails in times of conflict.
Although directly involved, European governments have not yet raised the issue of the future European security order. They tend to be busy supporting Ukraine and at the same time building up their own defences, within the framework of both NATO and the EU. There seems to be a general fear that Russia may attack NATO and EU members, once the war in Ukraine comes to a standstill (or even before). The default position in European and Russian thinking about the future is that Europe will be split into two major blocs: a Western bloc (including Central and Eastern Europe) versus Russia and some of its neighbours (including Belarus).[1] Similar to the Cold War, the two blocs may be separated by an «Iron Curtain», this time stretching from the Arctic to the Caucasus, living apart from each other. In the same vein, it is believed that we may enter an era of protracted confrontation with Russia. Some observers even recommend a new containment policy for Europe vis-à-vis Russia.[2]
The aim of this paper is to show that there are alternative, more inclusive scenarios. The end of the Ukraine–Russian war could be a historical turning point. Such moments in history open up the possibility to try to do things better than before. That will at least be the aspiration of many people on both sides of the ceasefire line. Under those circumstances, governments sometimes do manage to shift to a more stable security constellation (examples are the periods after 1815 and 1945); sometimes, they fail (as in 1918 and 1989). Remarkably, in the successful cases the loser of the war was included in the security order. Mutatis mutandis, when the loser was not included, it yielded a new period of instability and war.
This paper starts with a more analytical part that describes the differences between two fundamentally different types of security constellation: balance of power and collective security. Second, what would a peace agreement between Ukraine and Russia look like? In the third part,the question is raised of what the post-war security constellation in Europe would look like. What role is left for NATO, the Collective Security Treaty Organization (CSTO), the Organization for Security and Cooperation in Europe (OSCE), and the EU? Where would Ukraine fit in? And what about Russia?
[1] Ilya Budraitskis and Greg Yudin (2024): Overcomingthe rivalry between military blocs in Europe, in: IGRec Policy Papers,2024.
[2] Max Bergmann (and others) (2025): ALong-term Russia Strategy for Europe. Back to Containment?, in: CSIS report,July.
