One blindingly obvious consequence of Putin’s war is the damage done to global arms control (try convincing Washington/NATO to reduce their defence efforts after what we've just witnessed). There’s also a more technical aspect, albeit with a very politicised element. It concerns steps in the 1990s to convince Ukraine to surrender the nuclear weapons option. This article nicely summarises key points.
Hot off the press: here's an up-date on Russian nuclear forces, from the Bulletin of the Atomic Scientists.