British nuclear missiles risk being shot out of the sky by Vladimir Putin's new air defences

This, alongside the S-500, an advanced missile-defence shield capable of intercepting intercontinental ballistic missiles, has created a layered defence against nuclear weapons, a new report from Royal United Services Institute (Rusi) has revealed.

Rusi has warned the UK may no longer be able to guarantee the deterrent effect of launching a nuclear weapon.

It warns that without an American guarantee of support, Europe wil have to acquire or build their own hypersonic missiles to bypass Russian defence systems.

Dr Sidharth Kaushal, a research fellow for missile defence at Rusi, said enhancing Europe's long-range precision-strike capabilites was critical.

He said: "It is not certain that they [Russia] will intercept every submarine-launched ballistic missile but potentially also not a certainty that the required number will get through."

In the paper, titled Conventional Prompt Strike in European Military Power, Dr Kaushal wrote: "In the coming decade, an increasingly robust ballistic missile-defence system around Moscow may emerge, in the form of the A-235 and the S-500, which may form a layered defence."

Currently, the UK's nuclear arsenal relies on just four Vanguard-class nuclear-powered ballistic missile submarines.

Each sub carries up to 16 Trident II D5 missiles capable of delivering nuclear warheads, with each missile delivering 12 independently targeted warheads.

Dr Kaushal warned however that the Russians' anti-nuclear system might be able to shoot down a Trident missile before it deploys manoeuvrable re-entry vehicles, which splits one rocket into multiple targets.

The report said that unlike the US, Europe's nuclear powers Britain and France lack the scale of forces required to launch a robust and multilayered attack.

It added Israel and the US intercepted 90 per cent of two Iranian ballistic missile salvoes of approximately 200 missiles each in 2024.

The research also found factors driiving down the construction costs of building and enabling misisles could allow them to be fielded at a scale that means more targets can be struck.

Britain remains a long way off from developing hypersonic weapons, and the UK was denied direct access to the Security Action for Europe (Safe) programme which aimed to improve defence capabilities across the continent.

France called for the exclusion of the UK, and was in favour of a pay-to-play system in which the UK would have had to pay a fee to enter the programme.

The Safe programme has also been massively subscribed to across the continent, with proposals for a second iteration of the programme already in place.

Al Carns, the Armed Forces Minister, said Europe's rejection of the UK was a "self-defeating" move.

He said: "The UK is absolutely essential to European security. The UK is the cornerstone of European security given its geographical position as an island nation."

"To not allow us into the European defence fund is self-defeating. I think we are going to see far greater collaboration than before."

A Ministry of Defence spokesman said: “Our nuclear deterrent protects us every minute of every day and is the ultimate guarantee of our national security. We keep our nuclear posture under constant review so that we can adapt to the actions of our potential adversaries, including assessment of the defensive measures that they might use.

“This month we announced over £400million investment in long-range precision weapons, including hypersonic missiles, showing how we’re investing in critical new technology.”