Putin's warmongering means we must realise what he fears about UK's capability

Sir Simon Case, the UK's top civil servant until four months ago, may have just sparked one of the most urgent debates our country needs to have - the future of our nuclear deterrent, in the face of resurgent . This is far from easy territory, but we have to understand that Russia remains our most immediate threat and in the Kremlin there is one part of UK defence that they respect more than any other: our nuclear forces. To avoid war at the devastating scale last seen in 1945 - notwithstanding the terrible casualty count in Ukraine - we have to possess a credible deterrent that stops aggression in its tracks.

As such, nuclear weapons remain absolutely integral to our overall deterrence effort - but technology isn't standing still, and we have to recognise our shortcomings in this field. As the Defence Minister holding the day to day nuclear portfolio under the previous Government, one thing kept me awake at night: the patrol lengths of our Continuous At Sea Deterrent (CASD) nuclear submarines. This problem hasn't gone away: HMS Vanguard recently completed a staggering, record-breaking 204 day CASD patrol.

Certainly, the critical importance of our ability to guarantee a second strike from our on-patrol submarine means this method of delivery remains by far the most important. But our nuclear forces need to be even more resilient: both in terms of the submarine element, for example, through faster maintenance periods, but also by maintaining a posture that adapts to the evolving strategic environment - potentially, by diversifying our methods for delivering nuclear strike.

Sir Simon Case has suggested air launched nuclear weapons, like we had back in the 1990s, as one such alternative to complement our core CASD submarines. Arguably, this would deepen our deterrent to 'tactical' or 'theatre level' thresholds - where the likes of Russia have nuclear capabilities, but we have only conventional options.

The specifics of how alternative delivery mechanisms might work would clearly be highly complex and a major Government undertaking. Nevertheless, it's a matter of public record that the F35A stealth fighter, flown by a number of our European NATO allies, has been certified to carry nuclear weapons (noting we currently fly the carrier-compatible F35B). Alongside the F35, our other main combat plane is the Typhoon. In a recent article for the Spectator by three think-tank experts, it was suggested that "we could equip the British-French Storm Shadow missile with a low yield warhead", which could presumably be integrated onto the Typhoon - currently capable of carrying the conventional version.

All options in this space require careful scrutiny and a workable plan for funding. But this is a debate we need to have, not least to show our adversaries how serious we are about standing up to them. Sir Simon Case hopes that the Strategic Defence Review will deliver something tangible in this space - that may or not be realistic, but commencing a national discourse about our nuclear options would be very timely, and I for one would welcome it.