As the title says, does any NATO country's defense doctrine identifies radiation leaks occurred elsewhere, but presumably causing casualties in such country, as an equivalent of armed attack against it?

Here's a bit lengthy background/motivation/big picture. Not sure how could I make it more succinct.

Recently, I stumbled across these posts in a social network:

Let’s make it clear now:
ANY deliberate damage causing potential radiation leak to a Ukrainian nuclear reactor would be a breach of NATO’s Article 5.

Aug 19Tobias Ellwood MP, Conservative MP for Bournemouth East, Chair of the House of Commons Defence Select Committee, United Kingdom.

This really isn’t even up for debate. Any leak will kill people in NATO countries, that’s an automatic article 5
Aug 20Adam Kinzinger, Congressman, R-IL, United States.

I was wondering if that could be a valid assumption, so I did some (rather straightforward) research on the matter:

  • The Article 5 of NATO Treaty says (highlight mine):

    The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them […] will assist the Party or Parties so attacked […]

  • In order to trigger the Article 5, a country should declare itself being under an armed attack.
  • As far as I understand, such status should be declared by the executive branch of power, according to country's defense doctrine (military doctrine).
  • I checked the British defense doctrine and the U.S. National Strategy for Homeland Security and found nothing about the radiation leaks causing damage or casualties in these countries.

However, I think, some other NATO countries could have provisions about that. Are there any?

It is also worth noting that the Chernobyl disaster caused deaths and other health problems claimed in European countries. None seem to have triggered Article 5.

Also, the scale of possible disaster on Zaporizhzhia nuclear plant could be "10 times larger than Chernobyl", does that make any significance to trigger the Article 5?

  • Probably no, in general, but it would depend how intentional and how close it was etc. I suspect some might call for art 4 (not 5) consultations, depending on the exact circumstances. Regarding the Ukrainian claims of possible disaster magnitude, see skeptics.stackexchange.com/questions/53079/… Aug 23, 2022 at 3:07
  • 1
    This is going to be very hard to answer as it is going to deepened entirely on the details of the situation and they could react in very different ways depending on what they know about the accident.
    – Joe W
    Aug 23, 2022 at 12:25
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    By the same logic, a coal plant burning coal close to a NATO border would be an act of war? Pollution kills people, too. Aug 23, 2022 at 17:05
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    @bytebuster This was not an answer. Aug 23, 2022 at 20:35
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    We'll decide when we get there. There is no precedent on point.
    – ohwilleke
    Aug 24, 2022 at 8:25

3 Answers 3


Ultimately, this is a matter of international law, and as we've said many times before on this Stack, international law is customary, not legal. There is no body with the power to unilaterally enforce treaty provisions such as Article 5 of the NATO treaty. Each country determines for itself what its obligations are under Article 5. Such determinations would be informed by diplomacy, military strategy, and other geopolitical considerations, and perhaps also by the domestic law of that individual country.

Having said that, there are definitely some expectations around Article 5, which I would summarize as follows:

  • Article 5 is triggered by an intentional act of war. An accident such as Chernobyl is totally irrelevant, unless you're going to accuse the USSR of deliberately orchestrating it for the purpose of harming neighboring countries (which is false, of course). An intentional attack on a nuclear facility, however, might be a different situation.
  • Article 5 is not a toy. It is not to be triggered lightly or by mere provocations such as military exercises, troop movements, threatening public statements, or the like. Even something as explicit as the Zimmermann note would probably not qualify as an "armed attack."
  • Article 5 was not actually intended to be triggered at all. It was intended to change the MAD calculus in such a way that the USSR (and later Russia) would be deterred from invading Western or Central Europe (because that would result in war with the United States and other nuclear powers).

In practice, it would be up to the individual executives of each member state to determine whether an armed attack has occurred and what (if anything) they are going to do about it. NATO countries do meet regularly and can discuss the applicability of Article 5 if it becomes necessary, so it's not like each country is just making it up from scratch. But as mentioned above, nobody can force a country to commit troops that they do not wish to commit.

  • I'd argue about your last statement - although I'll readily admit I'm being a bit pedantic - you could feasibly threaten, blackmail, or use force against a much smaller country than your own to force them to commit troops they don't want to commit. You just need to be sure that whatever "persuasion" you're using is more enticing than the alternative of them turning those troops on you Aug 23, 2022 at 13:18
  • @ScottishTapWater I think he clearly meant that in the context of what the NATO treaty requires.
    – Barmar
    Aug 23, 2022 at 13:36
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    It is also not generally in any country's interest to predetermine specific kinds of action that would/wouldn't constitute an armed attack in advance, because that would enable adversaries to engage in piecemeal manoeuvres just shy of that line. This article on MAD makes the same broad point in a different context (the 'War Under the Umbrella' section): acoup.blog/2022/03/11/collections-nuclear-deterrence-101
    – dbmag9
    Aug 23, 2022 at 16:28
  • "Article 5 was not actually intended to be triggered at all." Well, it was triggered after 9/11. natomultimedia.tv/app/asset/408620 So treaties can be flexible like that, once put on paper. Aug 23, 2022 at 18:25
  • @Fizz: Hence the use of past tense.
    – Kevin
    Aug 23, 2022 at 19:12

A political judgement based on perceived intent.

Early gas warfare in WWI involved cylinders on the friendly side, opened when the wind was right to drift over enemy trenches. Only later was gas loaded into artillery shells. And since the tail end of WWII, military and security agencies were concerned about dirty bombs designed to spread nuclear materials.

I have no doubt that any deliberate release of nuclear materials where it can be expected to drift over the border would be an Article 5 case. NATO would probably consider it WMD use, too. Accidental release would be a different matter. But between deliberate and accidental release there is a whole range of reckless and careless attacks on nuclear sites, which require a political judgement of the event.

You should also keep in mind that the West has the right to defend Ukraine under the principle of collective defense. This does not require a prior treaty to be legal, all it takes is a victim of aggression and other countries coming to the aid. And not just in the Donbas but also in Vladivostok or Murmansk. President Biden declared that the US would not do that unless the conflict spilled into NATO territory, a political declaration with no legal force.

Since then, Russia and the West have exhanged public threats and declarations to influence each other. (Presumably private ones, too.) The Russian side likes to remind the West that Russia is a nuclear superpower, and not to be pushed into a corner. This involves wild threats on state-aligned media, military exercises, and so on. The Western side has been somewhat circumspect in what weapons they deliver to Ukraine to prevent further escalation..


There is already an answer which mentions that this is a

A political judgement based on perceived intent.

I would go further. Whether or not there has been an attack is a purely political decision. The US constitution gives Congress the power to declare war. And using casus belli is technically purely optional although it does go a long way towards convincing congresspeople that declaring the war is the prudent thing to do. There is no legal restriction, however, on when Congress may or may not declare war.

So if Congress votes to view it as a bona fide attack, it is.

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