It's pretty clear that NATO does not want to get militarily involved in the war between Russia and Ukraine. However a NATO country like Poland or Romania could still decide to send in troops to defend Ukraine on their own accord.

Let's say something like that were to happen and Russia starts bombing Poland or Romania in retaliation, would Article 5 still be invoked in such a case? The troops would only be sent in to help bolster the defense of Ukrainian cities. They would not engage Russian troops unless they were being attacked by Russian troops. Nor would these troops attack any targets in Russia or Belarus.

So if Russia decides to attack Poland/Romania for merely helping to defend the territory of Ukraine, would Article 5 still be invoked?


2 Answers 2


The comparison with Turkey's forces being attacked in Syria, even by Russia, (which did happen), isn't 100% relevant because Art.5 starts with

"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 [...]"

Syria is not Europe or North America. Ukraine is in Europe.

The part o.m. quoted is relevant still in the sense that NATO may decide it was an attack, but do nothing much about it. There's plenty of precedent for discounting isolated incidents/attacks, like NATO planes shot down by the Soviets during the cold war over Germany, over the Baltic etc. So some stray Russian shell killing a bunch of Polish or Romanian troops near the border will probably not result in WW3. It would take a more concerted attack than that.

  • this answer could be improved by also answering if exchanges on water, say the black sea, happened as suggested by this question in skeptics skeptics.stackexchange.com/questions/53057/…
    – Reed
    Mar 3 at 14:09
  • 2
    "Ukraine is inEurope by most definitions." Are there definitions where it is not?
    – Tristan
    Mar 3 at 14:22
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    @Tristan: see line D en.wikipedia.org/wiki/… which excludes a portion of it, for whatever reason. Ah, never mind. That was one sea away...
    – Fizz
    Mar 3 at 14:28
  • this (together with Georgia's recent application to join the EU) does raise the interesting question of where NATO considers the border to be. If Georgia does join the EU, and then NATO (obviously multiple if's there), would an attack on it be understood as an attack on all? I guess that'd be a question of its own though
    – Tristan
    Mar 3 at 14:51
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    @ksinkar Article 6 says "For the purpose of Article 5, an armed attack on one or more of the Parties is deemed to include an armed attack... on the territory of Turkey or on the Islands under the jurisdiction of any of the Parties in the North Atlantic area north of the Tropic of Cancer"
    – Smitop
    Mar 3 at 15:17

A single NATO member, Turkey, has sent troops to Syria and got attacked from Syria. NATO did not invoke collective defense.

Of course the overt military attacks on Turkey were hardly significant, and Turkey might not want foreign contingents to meddle in their anti-Kurdish guerilla war. But Article 5 says

if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area. [emphasis mine]

If Poland or Romania go against the consensus of NATO and attack Russia, they might find themselves alone. If Poland or Romania act as a conduit for arms transfers and get attacked over that, NATO would be much more likely to back them.

When you sign a policy with an insurance company, that contract will be interpreted and enforced by the legal system of your country. If they don't pay, you can sue. The NATO treaty is between sovereign countries. There is no court to sue in. That means their strength is in the credibility of the political promises. And that, in turn, depends on the perception of who was acting in good, or bad, faith.

  • 3
    But Syria is not Europe or North America. Ukraine is Europe by most definitions. "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 [...]" The part you've quoted is relevant still in the sense that they may decide it was an attack, but do nothing much about it.
    – Fizz
    Mar 3 at 7:39
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    @PMF You are misreading it. It doesn’t matter who attacks; it matters where they attack. Mar 3 at 9:07
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    @EmilJeřábek Makes sense. I had in mind that some (although minor) attacks from Syria where on Turkish territory. Of course, if Turkish troops are attacked in Syria that is different.
    – PMF
    Mar 3 at 9:44
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    @ChrisH, Article 6 explicitly includes all of Turkey.
    – o.m.
    Mar 3 at 17:38
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    @ChrisH, either that or one makes it a rounding error. The OP had different examples.
    – o.m.
    Mar 3 at 17:58

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