Strategic 'concertina effect'

Indeed, the Russians see the Sarmat super-heavy intercontinental ballistic missile as the weapon needed to penetrate future US missile defence shields.

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As for the US, there is also plenty of strategic uncertainty, with the rise of China as both a conventional and an increasingly nuclear peer competitor. Although from a relatively low base, Beijing is now expanding its nuclear arsenal at high speed, with estimates suggesting that China will have more than 1,000 warheads by the middle of the next decade.

To complicate matters, any step that the US takes against China - Washington's planned fleet of B-21 long-range strategic bombers, for instance, is primarily intended to be deployed over the Pacific Ocean against potential Chinese targets — will attract a Russian response as well.

Admiral Igor Kostyukov, who heads Russia’s military intelligence, has publicly argued that the deployment of US missiles in East Asia constitutes a threat to Russia’s Strategic Missile Forces. The result is a peculiar strategic “concertina effect”, whereby nuclear developments in China attract nuclear developments in the US, which, in turn, provoke a nuclear rearmament response in Russia.