Many people have asked me what I think the odds are of an imminent major US-Russia nuclear war. My current estimate is about the same as losing in Russian roulette: one in six. The goal of this post is to explain how I arrived at this estimate. Please forgive its cold and analytic nature despite the emotionally charged topic; I'm trying not to be biased by hopes, fears or wishful thinking.
My estimate is 30% x 80% x 70% ~ 1/6, as illustrated in the figure and explained below. The horizontal axis roughly corresponds to levels of escalation, while the vertical axis corresponds to how favorable outcomes are to the two sides.
Possible outcomes
To estimate the odds of pulling a spade out of a deck of cards, it's important to know how many suits there are. To estimate the odds that the current unstable situation ends up in the "KABOOM" outcome (a major US-Russia nuclear war that might cause nuclear winter and kill most people on Earth), it's similarly important to know what other reasonably stable outcomes it's competing against. The shorthand labels I've given these outcomes (grey boxes) should't be taken too literally: "Kosovo" & "Vietnam" refer to scenarios where one side wins outright (breakaway succeeds & Goliath is expunged, respectively). "Libya", "Korea" & "Finland" refer to intermediate outcomes involving simmering war, frozen war and full peace, respectively. I'm not showing the "Cuba" outcome (invasion averted by negotiated agreement) that was on the table in December 2021, since it's now off the table, as are resumed EU-Russia gas exports via the Nordstream pipelines.
Escalation dynamics
The grey ellipses represent relatively short-lived situations. We are currently in a vicious circle in the form of a self-perpetuating escalation spiral: since "Kosovo" is deemed unacceptable by Ukraine and the West while "Vietnam" is deemed unacceptable by Russia, both sides double down and escalate further whenever they fear losing. Such escalation has been both quantitative (more weapons, more mobilization) and qualitative (e.g., novel sanctions, heavier weapons, longer-range weapons, attacks inside Russia, scaled-up attacks on civilian infrastructure, shelling of a nuclear power plant, assassinations, sabotage of gas pipelines and Europe's longest bridge, annexations, and escalatory rhetoric about nuclear use). My assessment is that Russia, whose GDP is similar to Italy's, can no longer compete with the West in terms of quantitative escalation, and that Putin understands that his only chance to avoid the "Vietnam" outcome is to escalate qualitatively, with nuclear weapons use being his last resort. Last spring, I predicted that once loss of occupied territory loomed, he would annex what he controlled and start talking about nuclear defense of Russia's new borders – and here we are.
Breaking the vicious circle
I view it as highly unlikely (<10%) that Putin would accept "Vietnam" without first going nuclear, because it would almost certainly result in him being overthrown and jailed or killed. On the other hand, I also view it as highly unlikely (<10%) that the West would accept a "Kosovo" scenario where Russia is granted a peace deal where it keeps everything it's annexed, because if the powers that be in the West were that appeasement-minded, they would presumable have opted for a "Cuba" scenario in 2021 by acquiescing to Russia's demand that Ukraine never join NATO. This means that with high (>80%) probability, the current vicious cycle of escalation will end only with de-escalation into one of the intermediate outcomes ("Libya"/"Korea"/"Finland") or with lower-case "kaboom" (Russian nuclear use in Ukraine).
Estimates of the "kaboom" probability have recently ranged from 5% to 9% in the Metaculus prediction community. My current estimate is a few times higher (30%, e.g. a 2-to-1 chance that the cycle will end with de-escalation rather than escalation), because de-escalation currently seems so disfavored: there appears to be a widespread assumption in the West, shared by Ukrainian leaders, that Ukraine is winning and that Putin will grudgingly accept "Vietnam". Moreover, there is a near-consensus in mainstream Western media and policy circles against peace negotiations, exemplified by e.g. the hostile response to Elon Musk's recent suggestion of a peace deal.
Post-nuclear escalation
The probability that "kaboom" (nuclear use in Ukraine) leads to "KABOOM" (WW3) obviously depends on the Western response and subsequent escalation dynamics. My estimate is quite high (80%) that NATO's response will be forceful enough to include a non-nuclear military strike against Russia, because key NATO leaders and others have already made strongly worded statements to this effect. Options discussed have included sinking Russia's Black Sea fleet, which it would be difficult to imagine Russia not viewing as a declaration of war. My most likely (70%) scenario after that is Russian counterstrikes followed by rapid escalation via retaliatory actions from both sides, culminating in execution of the all-out nuclear war plans that both sides have spent decades preparing. My 70% estimate factors in that the long history of nuclear near misses has convinced me that both the US and Russia are much less competent in de-escalation than in escalation.
In the slightly less likely (30%) scenario that global freakout brings the US and Russia back from the brink, de-escalating toward the left side of the diagram, the outcome may be closer to "Kosovo" or "Vietnam" depending on who blinks first, i.e., on whether the de-escalation happens after "kaboom" or "Expansion".
WW3 impact
Many detailed estimates of nuclear war impact have been published in the academic literature. Xia et al (Nature Food, 3, 586–596, 2022) estimate that nuclear winter would kill about 99% of all Russians, Americans, Europeans and Chinese, with the most powerful post-war remaining economies being in South America, Southern Africa and Oceania. However, more work is needed to reduce uncertainties e.g. targeting scenarios, black carbon smoke production and lofting.
The only nuclear target map thus far declassified by the United States suggested that China would also be targeted even in a US-Russia war, to prevent it from emerging as the strongest post-war economy. My guess is that such a strategy is in force today as well, given the frosty state of Sino-US relations. Since China has much more large cities than either the US or Russia, this significantly increases my smoke production estimate.
I'd love to hear your thoughts both on this risk modeling framework and on the factor probabilities (30%, 80%, 70%) listed in the figure! I'll plan to update them regularly as the geopolitical shituation evolves.
De-escalation clarification
Many Twitter responses to this post have conflated nuclear de-escalation with capitulation or appeasement. Conversely, not all escalation has military value. For example, goading Putin to escalate with Moscow car bombing or viral video taunts is arguably against the national security interests of Ukraine and the West. If you're generally opposed to de-escalation, I'm curious as to which of the following escalations you don't want both sides to stop:
1) nuclear threats
2) atrocities
3) assassinations lacking military value
4) infrastructure attacks lacking military value (e.g. Nordstream sabotage)
5) shelling the Zaporizhzhya nuclear plant
6) misleading disparagement of de-escalation supporters as unpatriotic or appeasement-seeking
People interested in nuclear security and this post might be interested in applying to the Spring 2023 Internship Program at the Nuclear Threat Initiative, a non-profit working to prevent global catastrophic risks by driving systemic solutions to nuclear and biological threats imperiling humanity. Applications are due by Friday, October 21.
This is a test by the EA Forum Team to gauge interest in job ads relevant to posts - give us feedback here.
Hi Sarah,
Do you know if anywhere in the UK has programmes such as this?
Thank you
Thanks for asking! I'd suggest looking at the 80k Hours job board filtered by "nuclear security" - for example, I see the Junior Policy Fellow position at the Centre for Science and Policy in Cambridge, UK. Hope that helps! :)
This post is several orders of magnitude more pessimistic than the views of the Samotsvety forecasters (as of 3 October 2022):
https://forum.effectivealtruism.org/posts/2nDTrDPZJBEerZGrk/samotsvety-nuclear-risk-update-october-2022
It's also much more pessimistic than other serious commentators I've read (though I'm not following closely). See e.g. Trey Howard (also ~3rd October):
https://marginalrevolution.com/marginalrevolution/2022/10/trey-howard-arguing-nuclear-risk-is-low.html
Critical discussion of this post on LessWrong: https://www.lesswrong.com/posts/Dod9AWz8Rp4Svdpof#comments
It's also much more pessimistic than are prediction markets – for instance, Metaculus puts the odds of a nuclear detonation in Ukraine by 2023 at 7%, and a Russian nuclear detonation in the US this year at ≤ 1%.
I am also confused by the suggested outcomes, e.g. I don't see how Russian victory could be either analagous to Kosovo or accurately described as "breakaway succeeds", since Putin has now abandoned the pretence of seeking to support DPR/LPR as independent states. I would suggest the following are rough possible outcomes:
I think it's clear that at the start of the war, Ukraine would have viewed 7 and certainly 8 as victories, but now only views 9 as a victory. Russia is hard to read, but I would guess that something like 3 was the initial war aim and that they would now be content with 4.
The question is, is there a deal there? E.g. would the belligerents settle for 7? At present, I think the answer is a firm no from both sides, so the war continues. Both sides currently believe they can do better on the battlefield than the best deal they could achieve by a negotiated peace and the war will continue until that is not the case.
The question at hand is, can Putin improve his position by using a nuclear weapon? This I think is where OP goes wrong. 1 is not a good outcome for Putin, but Putin calculates just as we do that the use of a nuclear weapon in Ukraine has a high probability of leading to an escalation sprial and then outcome 1. Another possibility would be that Russia folds in the face of NATO escalation, in which case outcome 9 occurs, which is also bad for Putin.
The only "good" possibility is that NATO declines to respond, but that would likely only be the case if the nuclear weapon use were relatively inconsequential. But if it was inconsequential, it would also fail to alter the course of the war.
Also, Putin is probably genuine (though mistaken) in considering Ukraine to be an integral part of Russia, and he likely wouldn't want to nuke sites he considers culturally important to Russia. Ruling over the smouldering ruins of Kyiv is probably not an outcome he favours.
What is said by OP, is that Putin personally wouldn't survive outcome 9, but why should this be? He successfully ruled Russia without Crimea for many years. Either he rules Russia with a hand of iron or he doesn't. If he does, he can survive withdrawing to the internationally recognised border. If he doesn't, he's probably toast already. Either way, he isn't actually improving his position by using a nuclear weapon.
In conclusion, I don't think there is a rational use case for nuclear weapons here. The risk is that Putin may behave irrationally, and for that reason I put the risk at around 5%. I concur in OP's calculations after that point.
Outside view: OP says <10% chance Putin would accept losing without first going nuclear, but also says, "there appears to be a widespread assumption in the West, shared by Ukrainian leaders, that Ukraine is winning and that Putin will grudgingly accept "Vietnam"." There is no sufficient reason for OP to prefer his own analysis to that of Western and Ukrainian leaders.
Thanks for writing this Max.
I believe the risk is less than 1%. Here are some quick thoughts on why, adopting your framework.
(I am not an expert on Russia, Ukraine, or nuclear war; these are just rough comments)
Odds of Russia using a nuclear weapon in Ukraine in the next year
I put this around 10%. I have the highest uncertainty here, as it's hard to understand decision making processes in the Russian leadership from abroad, Russian nuclear doctrine is (purposefully) opaque, and escalation dynamics between a nuclear and a non-nuclear state are not well understood.
Yes, Putin's nuclear signaling has grown more aggressive recently, and Russian strategists do not seem to believe that limited nuclear use would necessarily lead to uncontrolled escalation, so they may be willing to countenance the use of smaller nuclear weapons against military targets.
But I'm lower than you because:
(1) While Russia's military doctrine relies on heavily on nuclear weapons, it involves more coercion through threats than actual use, so nuclear signaling from Russian leaders shouldn't surprise us.
(2) It isn't clear what military objective using nuclear weapons would achieve. Russia would have to use several to truly cripple the Ukrainian military, and nuking a big city like Kyiv would serve no military purpose while alienating the major countries that are still friendly to Russia.
(3) Russia's response to the Kerch Strait Bridge attack was very muted. The bridge is a key supply line for Russian forces in the south and a major part of Putin's legacy. Russia has not turned the rhetoric up in response to the attack, instead accusing Kyiv of terrorism, not crossing a red line.
(4) A generalization of (3)—I don't think we're in "a self-perpetuating escalation spiral." Neither side has openly escalated the war outside Ukraine's borders; Russia hasn't used chemical weapons despite fears it would; and the U.S. seems to be working to restrain some Ukrainian escalation (e.g. the recent story about U.S. officials opposing Ukraine's alleged attempt to assassinate Dugin).
(5) From public reporting, U.S. intelligence doesn't seem to think Russia is preparing for nuclear use. The U.S. has had very good insight into Russian plans since months before the war started and would probably be able to tell if Russia was moving weapons from storage sites, preparing warheads, etc.
Odds of a U.S. conventional military response directly against Russian targets
I think there is maybe a 25% chance of this. In 2016, the U.S. ran a wargame premised on a Russian invasion of the Baltics followed by a nuclear attack on responding NATO forces. The National Security Committee Principals Committee (Joint Chiefs + some Cabinet members) recommended a nuclear attack on Belarus in response, aiming to avoid escalation but preserve deterrence. The NSC Deputies (the next rung down) recommended a conventional attack on Russian forces and an attempt to rally the world against Russia for breaking the nuclear taboo. Some of those deputies are now principals, Biden himself is generally fairly dovish, and that wargame involved a scenario where Russia had used a nuclear weapon on a NATO country. I think the odds of a direct military response to a nuclear attack on a non-NATO country are much lower.
The U.S. has taken significant care not to cross any Russian red lines so far. U.S. decisionmakers universally rejected a no fly zone; the U.S. has held back on a lot of advanced military hardware, like fighter jets, that could enable Ukraine to strike Russian territory; and U.S. leaders have fairly consistently signaled that there needs to be a negotiated solution.
I'd expect the U.S. to respond by giving Ukraine greater capability to launch conventional counter-attacks than it has so far and by trying to get China and India to pressure Russia to end the war. For a direct military response by the U.S. to make sense, it would have to be signaled beforehand (probably, but not necessarily, publicly). It's important to separate commentary by those outside the administration from those within it. As far as I know, no actual decision maker in the US (president or NSC principal) has threatened such a response.
Odds of full nuclear war if the U.S. does respond directly
I put this around 8%. It is one thing for Russia to nuke a non-NATO country; it is quite another to nuke NATO itself. Russia's leaders all have long experience dealing with NATO and have no illusions about the consequences of a nuclear response to a conventional NATO attack. Backing down to NATO, which Russians realize is a stronger adversary, is also a lot more politically palatable to Putin than backing down to Ukraine, which on paper is much weaker.
I read the history slightly more optimistically than you do. Able Archer is often cited as the most dangerous moment, but more recent research suggests that the Soviets were not as worried about an attack as previously thought. The biggest danger from the Cuban Missile Crisis was that Kennedy and Krushchev didn't know everything their own forces were doing, not that either of them wanted nuclear war. Military command and control is significantly better today, the US and Russian militaries have well-established lines of communication, and much of the danger you're positing seems to come from reckless behavior by Putin that I don't think his track record justifies. I agree, however, that the U.S. and Russia are much better at escalation than deescalation.
This doesn’t give a lot of information about why Putin is insecure or vulnerable to being deposed, which is key to your argument for escalation. It’s plausible that in the resulting scenario, the majority of people will resignly accept the regime and its security forces. It’s unclear what internal forces exist that would act against Putin or what incentive they would have.
In LessWrong, a user brought up comparisons with other despostic regimes which faced failure, in Iraq and North Korea (who both endured great impoverishment postwar). The leaders in those states sat in the failure comfortably. Your reply seemed vague.
Why would a response to a massive invasion of cities, be similar to enemy forces reacquiring territory to their prewar border? If defeat in Ukraine was existential, wouldn’t we see evidence of this sentiment already—instead of massive waves of fleeing men?
That outcome doesn't seem evidence of insight, the ISW made a similar one that fits their narrative about Russian posturing[1].
The “labels” (“Finland”, “Libya”,...) seem confusing , they reference/suggest implications that seem complex and don’t clarify thinking:
It’s unclear why these labels or any labels were chosen, and it’s plausible they are evidence of confused reasoning, which reduces credibility.
It’s doubtful why you believe this.
Biden and command aren't lonBiden and command would need to sign-off on the most gratuitous murder in human history for speculative reasons. Your target list is literally from 1956, when the US had a very different perspective and worldview.Also, China has nukes now specifically for a second strike. The US does not expect China to be content with hundreds of millions dead and maimed for no reason.
As ISW wrote in May: “The Kremlin could threaten to use nuclear weapons against a Ukrainian counteroffensive into annexed territory to deter the ongoing Western military aid that would enable such a counteroffensive
If you're wondering: this does appear to be Max Tegmark of FLI / Life 3.0. My view on this comes just from looking at the LessWrong profile that posted the original.
Though I buy the argument that the risk is much higher than we think, the specific logic here probably underestimates the likelihood that Putin himself as the weaker party de-escalates VS actually uses nuclear weapons in the first place.
His pattern of behaviour thus far has been that of an opportunistic gambler - he does whatever he can get away with at the lowest cost to him, often resorting to bluffing and threats (including nuclear threats, this is not new), but will go no further.
If you give him what he wants without a fight, he'll say "fantastic" and move on to the next prize. When things aren't going his way he will try "please just let me win or I will use NUCLEAR WEAPONS" on the off chance it works. When it doesn't he just forgets about it and starts plotting his next gamble.
A few past examples establishing the pattern:
This isn't the behaviour of a madman - more like that of a careful predator who would very much like to eat you if you would so oblige, but also very much like to survive.
(Another potential giveaway is the hidden palace as well as all the stolen billions. He may hold deluded reactionary opinions but is not personally deluded enough that he cannot appreciate the finer things in life. You are more likely to find a messianic kamikaze type in a cave or a bunker, modelling austerity for his troops.)
Given that there are many ways Putin could live, stay in power, and even save face without using nuclear weapons - "declare victory, end conscription, go home" and "ruthlessly get rid of any internal opponents" being a few of them - my prior is that it is much more likely he will use one of those in a Vietnam scenario.
Of course none of this means we should argue for escalation on our end, the situation is dangerous enough as it is.
I haven't read this post (and that's okay - it has a big headline that I think will scare people, so I'm responding to that)
Does Max have a forecasting track record I can see anywhere?
Again, looking at the headline only, think this is 10 - 100x too pessimistic. I don't tend to respect the calibration of the median very clever person, so I don't intend to update a lot on the headline alone.
I imagine I'll read the full article later.
I think it's very easy to defer to "big names" but here I don't see a lot of reason to unless they have a good track record or specific expertise. Again, I could be wrong, but I think Max is a renown physicist without a forecasting track record, so I will treat this as I would any other forum poster.
This isn't meant as an insult to Max, I just think this article would be easy to overrate.
I'm happy to bet at 20% that Ukraine will get Nuked. Profit donated to charity. Happy to bet from counterfactual non-donations up to $200.
Max - thanks for this analysis, alarming though it is.
Apart from Putin's potential irrationality, I'm also concerned about Biden's state of mind.
Many reasonable people have observed that there seems to have been a gradual decline in Biden's cognitive functioning, verbal fluency, memory retrieval, etc. over the last several years.
This raises the question: who would actually be in charge of the US strategic nuclear forces, and who is actually setting policy about our potential nuclear response? No doubt there is an 'inner circle' of advisors such as Biden's chief of staff, national security advisor, joint chiefs, Jill Biden, etc., but it's unclear which people actually hold the most influence, what their risk-aversion levels are, how well they understand the implications of thermonuclear war, how well they understand the relevant game theory, etc. (This isn't a partisan issue; I can imagine people being equally concerned about Trump's decision-making if this had unfolded a few years ago.)
In other words, I worry that there's a power vacuum at the highest levels of US decision-making, and this makes me a lot more worried that I would be otherwise.
The US's stance so far reassures me. They have made clear they don't want nuclear war and understood that a No-Fly-Zone was a no-go.
That's two positive decisions in my book
From a nuclear risk perspective I am glad that whoever is making decisions is making them well.
PS people who disagreed with my comment -- do you disagree that Biden has suffered some cognitive decline, or disagree that there's a power vacuum, or disagree that his advisors have relatively unknown levels of risk aversion, understanding of game theory and nuclear war costs, etc.?
Genuinely curious.
I don't know enough to disagree or agree (and didn't vote on your comment) but my vague sense is that Biden's inner circle is about as competent and value-aligned (when it comes to nuclear risk) as you can hope for in a White House administration today. I base this only on what I've seen them do so far, but leave this comment here for others to agree/disagree vote on.
I upvoted this, but it's not like I have a clear idea of what Biden would do, cognitive decline or otherwise. I don't necessarily expect people from the same political camp as me to also have the same risk tolerance or priorities in general. And I suppose there's always power in that hidden inner circle.
This analysis is overly simplistic and highly flawed. The main issue with this model is that nuclear escalation is a 2 player game, but there is almost no analysis of the actual motivations and payoffs of each player.
As others have pointed out, the odds of being overthrown if russia withdraws are very far from "almost certain". Dictators are actually pretty good at holding onto power, even in the face of destabilising force. Also, attempting to use nukes could also trigger an overthrow, possibly with greater chance.
If russia tries to use a couple of tactical nukes on the battlefield, it does not guarantee any victory. Ukraines army is spread out, and would only get more motivated seeing their country attacked. The US abandoned it's tactical nukes for this reason.
Now, looking at NATO's perspective, if russia uses tactical nukes, assigning a probability of 20% of no NATO response is ridiculous, it's closer to 0%. If they let that precedent stand, then any nuclear power would be able to nuke and annex any of their neighbours with impunity. They have to establish the precedent that using nukes in a conventional war is counterproductive, or risk endless nuclear attacks in the future, by inflicting damage on russia that cancels out the benefits of the tactical nukes.
If putin does deploy nukes, and then nato responds by sinking their fleet or whatever, what is the motivation for putin to escalate further? Nuclear war is still a loss for russia. He would be placing everything on a gamble that NATO gives in to nuclear blackmail, when they literally just demonstrated that they wouldn't.
The smart move for Russia is to continuously threaten to use nukes, but never to go ahead with them. The threat of nukes is keeping NATO out of the war, limiting what arms ukraine recieves, and diminishing support for ukraine from westerners scared of nukes. All that goes out the window if they actually do the insane thing. Not using nukes is the tactically sound option here.
Really, the actual question you need to ask is how insane Putin is, and whether he mistakenly thinks the west will give in to nuclear blackmail. If he's at all rational, the nukes are staying in their bays.
Two issues raised by the idea of global power shifting towards the Global South: a) if WW3 started tomorrow, I think the chance of Brazil and Mexico (approximately half of Latin America's population) remaining stable democracies is less than 1/4. And I don't know what could happen to India and Pakistan. Either we'd have dictatorships (like in WW2 and the cold war - but possibly worse), or civil war. And notice, especially in Brazil, the rising political power of the military and charismatic churches makes things worse. b) would a post-nuclear world be one where WMD are seriously oulawed (like Harbingers in Palmer's Terra Incognita), or quite the opposite (i e., a race to the bottom where every country would need a stockpile of WMDs to ensure sovereignty)? I think the former is more likely: without international pressure and some coordination among nuclear powers, it's quite likely that many other countries would have nukes (or bioweapons) today.
I think Tegmark is still too optimistic. The arguments against nuclear war happening are typically very weak (variations of "it hasn't happened yet, people believe in MAD, leaders are rational). And even when pundits have considered the risks higher (Cuban missile crisis) their actions have not reflected this at all. We should take this as a signal of massive status quo bias and denial.
http://www.mcgannfreestone.com.au/?p=2255
https://forum.effectivealtruism.org/posts/ysBDfX6AhJpswrQxj/the-danger-of-nuclear-war-is-greater-than-it-has-ever-been
To prevent nuclear war, we need a movement aimed at the elimination of nuclear weapons and compliance with the Treaty on the Prohibition of Nuclear Weapons. Back from the Brink in the United States is a growing movement with real potential to impact nuclear weapons policy and the prospect of nuclear war. Learn more at the link above.