Britain and France have publicly committed for the first time to coordinating their independent nuclear deterrents in response to extreme threats, signalling a new phase in bilateral and NATO nuclear strategy.
The joint declaration, signed during President Emmanuel Macron’s state visit to London, affirms that the UK and France maintain sovereign nuclear arsenals but are now prepared to align them in the event of a major crisis. It states unequivocally that “any extreme threat to Europe would prompt a response by both nations.”
This is the most explicit public statement yet of the two countries’ willingness to coordinate nuclear posture and response. Until now, both have emphasised independence as the foundation of credible deterrence. The change reflects growing concern about Russia’s nuclear rhetoric and wider instability in the Euro-Atlantic region.
Prime Minister Keir Starmer hailed the agreement as a milestone in European defence. “As close partners and NATO allies, the UK and France have a deep history of defence collaboration and today’s agreements take our partnership to the next level,” he said. “We stand ready to use our shared might to advance joint capabilities while keeping our people safe.”
The UK and France are Europe’s only nuclear-armed powers and two of NATO’s three nuclear states, alongside the United States. Though both nations contribute separately to the alliance’s deterrent posture, this declaration goes further, raising the prospect of integrated decision-making in scenarios involving existential threats.
Defence Secretary John Healey said the new posture underlines shared resolve. “This partnership strengthens our leadership in Europe and sends a clear signal to our adversaries that we stand stronger, together,” he said.
The declaration is part of a broader update to the Lancaster House treaties, including a reinforced Combined Joint Force with cyber and space capabilities, and closer integration across strategic planning. Officials say it reflects a maturing of UK–France defence cooperation after years of joint deployments, industrial collaboration, and shared nuclear research.
By formalising coordination at the highest level of deterrence, London and Paris are aiming to deter adversaries through a united nuclear front, while also demonstrating European strategic autonomy within NATO’s framework.
NATO is a ‘nuclear alliance’ that is already supposed to coordinate decision making in the event of conflicts up to and including nuclear exchanges, which is why for example, German aircraft are certified to carry US nuclear warheads. Britain’s deterrent is an asset committed to NATO for most scenarios, with the option to use it unilaterally in support of ‘supreme national interest’. France, as far as I’m aware, does not commit its nuclear forces to NATO, so does this actually just boil down to France expressing a willingness to make a somewhat similar commitment to the UK and the US? The scale of French and UK arsenals are sufficient for national deterrence, but I don’t believe they are sufficient to provide a ‘nuclear umbrella’ to the whole of European NATO without US support, so this all strikes me as political hot air with no significance at the coal face.
6 SSBN plus French air launched nuclear armed cruise missiles and the UK future F35A free fall nukes, neatly 550 warheads today.
And you don’t think that combined force is enough?
Just to throw in a useless bit of info, there have been over 2600 Nuclear detonations so far (al but twol of which have been on uninhabited areas) and the World is still here.
I know, it’s not an “Eggs for Eggs” comparison but I just thought I’d chuck it in.
“Behold, I am the destroyer of Worlds”.
Ok, well as you are known for your imagination, try to imagine the result of a) those 2600 explosions had all been on inhabited cities and above ground and b) if 32 submarine launched MIRVed missiles with maybe 128 to 256 warheads were launched at your country from 1 UK and one French.
In the case of a) civilisation ending? Maybe.
Would b) deter you in any way?
Ha.
I guess my “bit of useless info” and it’s acknowledged “Not an Eggs for Eggs comparison”, failed to hit the target completely then !
“Imagine that”.
that is such a weird equivalence…today, 2025, it would take one nuke lobbed on a city wherever it may be to effectively herald the apocalypse..
As a person who has studied this very scenario for decades now (retired and way less serious about stuff on a chat site !) I tend to understand the consequences of even a single device being detonated on a city, wherever it is.
“Whoops, apocalypse”
It’s a good point particularly in regard to some of the more outlandish claims from the Cold War about nuclear winter. Nuclear weapons are pretty small compared to even small asteroids.
A limited exchange of dozens of weapons was unlikely to have long term effects. We tested that many in the atmosphere before the LTBT.
If you have 6 SSBN’s at sea it’s enough for a counter force mission but if only two at sea (1 each) then it’s only enough for a counter value response.
Basically counter force is where our trident missiles launch to take out land based Russian ICBM’s in an attempt to fight a nuclear war without killing a lot of people. With the USA’s large arsenal this is what we can participate in as part of NATO.
France only has a counter value deterrent, basically glassing the top ten cities in Russia. The UK deterrent on its own can only do counter value by hitting an enemies cities as a deterrent.
Britain and France combined could conceivably execute a counter force mission if they increased up tho their full warheads load of around 1,000 warheads. If they coordinated their SSBN deployments they could come up with a similar sized force to the USN or Russia SSBN’s.
This announcement does not provide for any kind of combined mission. It’s more of a statement of intent concerning US withdrawal from NATO.
If two boats unleashed their entire load on Russian cities that would be the total end of Russia as a functioning country, that’s MAD the whole point of nuclear deterrence not launching at their ground based missile silos.
That’s now how anyone planned to fight a nuclear war after the 60’s.
MAD was never doctrine.
Jim both sub fleets are ancient so 3/4 is best case scenario, which is why I keep banging on about a 5th Dreadnought. There is a window of opportunity to do that without undue delays to SSN(A), but it’s literally very tight now.
It needs to be in the Autumn DIP really.
I agree, I was only responding to redshift comment on 6 which I think is unfeasible with current fleets.
But 6 boats with 500 independently targeted warheads is roughly what is needed for a counter force response. This similar to USN plan.
You could maybe do something similar if Britain and France had 5 each and coordinated.
Totally agree Jim, it’s a ref election of not necessarily being sble to count on the US and realisation (not just recent but recently focused upon) that the US would not necessarily nuclear respond to a nuclear strike on Europe. Many strategists, generally when not strategically biting lips and holding tongues have admitted to that and the Russians are not only are aware of it but have done their best to widen the gulf between one and the other events taking place. Thus this measure is important in raising doubts in Russian thinking emphasising that Europe has an independent deterrent whatever its commitment to a UScentric NATO the US focus of which only feeds the Russian one eyed, unsophisticated thinking on their strike and potential response strategy/risk. Even the unknown quantity of UK/France cooperation doubles the risk to them and notes that a nuclear strike isn’t just a US controlled option which Superpowers can easily focus heavily upon and discount others, especially a monolith, inflexible State like Russia, the bludgeoning unsophisticated nature of which has been shown particularly in Ukraine.
It’s vital to to make clear, as it takes joy in the ructions between Europe and the US that any presumption it can ‘conquer’ Europe merely by its nuclear threat will have nuclear consequences it can’t quantify, doubt is the real deterrent and certainly one only has to look at US attitudes to Nth Korea and Pakistan to see how even totally unequal threats still focus minds and affects decision making. It’s also the binding together of something new whereby UK and France are starting upon a road where far closer and increasingly flexible nuclear cooperation develops. Again even the fear of that can have a deterrent effect and certainly well beyond nuclear, Europe needs to be taken more seriously militarily by Russia and indeed China if it’s to flourish in the new developing World Order. Clearly decades of disarmament hasn’t had the required effect.
How do you come up with 6 SSBNs ? There are 4 each, so 8 overall, 2 will be in maintenance / refit at anyone time. So that leaves 6 and you cannot have them all deployed at once as the crews do actually need to go home so at least 2 will be at home. That leaves just 4 available and that is if everything is working properly with zero defects, full manning levels, no training required etc etc etc.
Then things get complicated as both countries with planned deployment, training, maintenance / refit / LOPR schedules planned out for decades and each one is very different. That’s driven by us because we use different fuels (HEU/LEU), hence different Refuelling intervals (French boats every 8/10 years, ours are 20/25). And just because a refuelling isn’t required doesn’t mean maintenance / refit / updates aren’t.
Both the Vanguards and Triomphant boats are getting long in the tooth so things do go wrong, which probably explains why Vanguard class deployments are now Marathon sessions.
Given all of that it should in theory and with excellent cooperation in planning and coordination to run 8 very different boats so that 3 are always at sea on Patrol. That may not sound like much but there would also usually be one in Transit as well so 3/4 is a 150/200% increase in Deterrent.
It’s not all doom and gloom we are both building New Boats which should be more reliable so things will be easier.
What would really help is if PDQ (like in UKs case this year) we each commit to a 5th boat, integrated targeting plans etc.
10 Boats may not sound a lot when Russia has a planned force of 14 and that has to be split 50/50 over 2 oceans and ours don’t, so it’s quite a Big Hammer we would have to wave at Mr Putin.
Good point, integrated targeting plan should also be agreed. I suspect the French are reluctant on this point however.
Said 6 meant 8
Spilt my coffee ! 😂😂😂
The tactical nukes are US-controlled, so if you want to include them in the equation then you’re assuming a NATO response with the US behind it, and the combat mass of UK/France alone becomes less relevant. So assuming only independent strategic weapons are relevant- for reasons of maintenance, training etc, you’re looking at potentially 2-3 UK/French boats deployed to provide deterrence. If the US wants to get involved then it’s a NATO operation anyway, so assuming they don’t- say Russia decides to start dropping strategic weapons on German cities, do you retaliate with one or more of your boats, giving away their position (allowing them to be targeted) and potentially leaving you without a second strike capability in the event of a subsequent attack on your own country? There is a grim Cold War era joke to the effect that ‘a tactical nuclear weapon is one that lands on Germany’. The point is that an adversary knows that an attack on our territory would result in a cataclysmic response, but with so few boats we can’t extend that guarantee to every other country in NATO with the same level of credibility, unless we are prepared to effectively eliminate steps on the escalation ladder that we’d probably rather not. The Americans can- because they deploy enough boats that they could lose some and still retain the capability.
Why is that grim?🧐
Not retaliating means that deterrence has failed, and the next target is likely to be us on the assumption that we won’t retaliate to that either.
That would be a pretty stupid assumption, well maybe if we had elected Corbyn.
UK to buy into ASN4G for Tempest, fitted with sovereign warhead?
One minor problem with us launching nukes at Russia. We would all be dead. MAD really…
The idea behind ASMP and ASN4G is as tge French say a “force de dissuasion”, its the final warning shot before going Strategic. The idea is if there is a war and Russia uses a Tactical Battlefield Nuc we can retaliate tit for tat, if they use one against a civilian target then they get a stand off missile back in one of theirs.
The hope is that as we have displayed resolve by replying with equal force then someone has the good sense not to go any further. That may sound fanciful but it’s a damn bit more sensible than us launching a sub strategic nuclear weapon from a Trident Submarine, how does Russia know the difference 🤔
Well I think it’s about making the opposite as true as possible also. Russia may be a vast State (though not as vast as non globe maps show it) but its major cities and populated areas constitute an area more akin to Western Europe so they are much more vulnerable that at first imagined as Goat herders aren’t really capable of sustaining a Nation. It’s not like Russia survives as a functioning Nation and we don’t and of course much of what’s left of it in the East would be absorbed by a China deeply focused on the great national insult of losing those lands in the first place. Russia is terrified of latter scenario anyway which is why it has tied itself so closely to be useful to China but equally knows that just delays that risk. It needs to dominate Europe one way or another to have any hope of fending off China even if it’s a century down the road.
Time for me to get in the comfy chair and read all the incoming comments from the Nuclear “Experts”.😂
Not an expert in anyway but at the end of any NBC training we were reminded that the most important drill was to ‘bend over and kiss your arse goodbye’👍
At my age, that would cause a fair amount of pain now.
I’m pretty sure H&S will have amended that advice by now😊.
Do you think? The old ‘but we have always done it that way’ policy is powerful in this Country which is a major reason why we have declined so far since the war.
Username checks out 🤡💩🤣