The Russian invasion of Ukraine has undermined many of the assumed truisms on which international relations have been based since 1945. Nations would not invade other nations unless this was manifestly necessary in self-defence, for instance. In armed conflicts of whatever kind, civilian populations must be protected from harm. Humanitarian assistance must be facilitated. Minority rights must be respected.

The Western democracies are now thinking through what a redrawn geopolitical map might look like if these moral and legal obligations are no longer in place, as appears to be the case in Ukraine. In many ways it is a frightening world. Countries bordering Russia and what it claims as its sphere of influence feel deeply threatened. This has had a dramatic effect on Nato, forging a degree of unity hitherto missing, leading some countries outside Nato to consider joining it, and obliging its members to reassess the share of national resources they apply to defence.