The missile that landed in the Polish town of Przewodów yesterday and killed two civilians turns out not to have been a Russian attack. This morning, NATO Secretary General Jens Stoltenberg confirmed that the Przewodów incident was, in fact, most likely caused by a Ukrainian missile, which inadvertently hit Poland while attempting to defend against Russia’s latest bombardment.
To some extent, Stoltenberg’s confirmation should not have been a surprise. Even last night, Polish President Andrzej Duda was careful to make clear that “[w]e have no evidence at the moment that it was a rocket launched by Russian forces.“ President Biden similarly noted that “preliminary information” suggests that “[i]t is unlikely [the missile] was fired from Russia.”
Yet for a few tense hours, the fear that the event would escalate into a direct conflict between NATO and Russia was very real and in many ways well founded. All we knew was that something explosive landed in Przewodów, near the border with Ukraine, and that the Polish government believed it was “most likely a Russian-made missile.” The incident took place on a day on which the Russians launched scores of missiles at Ukraine, so the notion that Russia might have launched the attack was certainly plausible. And while Russia denied any involvement, its past record of misrepresentations of such events has rendered its word largely useless.
The spilling over of the Ukraine conflict into NATO territory would be extremely dangerous. NATO supports Ukraine, but it is not obliged to fight Russia on behalf of Ukraine. On the other hand, an intentional attack on Poland, a NATO member, would be an attack on a country other NATO members have committed to help protect. The United States in particular has made clear that it is prepared to defend “every inch of NATO territory” from Russian attack, a point the Biden administration has reiterated time and time again. So a missile hitting Polish territory is a grave matter; the killing of civilians there is, too; and evidence that this was an intentional act on the part of Russia, as opposed to an accident, would almost certainly require some sort of response. No doubt this is why, at the request of Duda, NATO leaders scheduled a meeting for today to figure out how to respond.
We prepared this overview of the international law governing an event like the Przewodów incident in anticipation of this meeting, so as to help readers understand the factors that might go into any NATO response. Even where the facts are unclear, the law surrounding such incidents is relatively well established, if at times contested. And while this incident thankfully proved not to be a result of Russian action, this legal framework is still worth considering, as the next missile to land within the territory of a NATO country may not be an accident of Ukrainian air defenses.
Whether an attack or not, the Przewodów incident was undoubtedly a violation of Poland’s sovereignty. Had Russian military forces done it, even accidentally or unintentionally, then Russia would be under an international legal obligation to accept responsibility and provide Poland with full reparations as well as credible assurances that no further violations will take place. The same is likely true for Ukraine if it is responsible, though Ukraine may be able to argue that it was acting in self-defense and Poland may, in any event, waive any international claims it might otherwise have against Ukraine out of acknowledgment that Ukraine was acting in response to Russia’s unlawful aggression. Even if irregular forces or other non-state armed groups in and around Ukraine had somehow caused the incident, Russia or other states might be held responsible depending on their relationship with those groups. Had Russia been found to be responsible and failed to meet these obligations, then Poland and its allies might have been able to take measures to induce Russia to do so, up to and including countermeasures that temporarily suspend some of Russia’s own rights under international law until it returned to compliance.
One thing Poland and its allies would not necessarily be able to do, however, would be to respond with military force. As reflected in Article 2(4) of the U.N. Charter, international law bars states from engaging in “the threat or use of force against the territorial integrity or political independence of any state,” including in response to violations of their sovereignty. That said, Article 51 of the charter also provides for an exception where a state is exercising its “inherent right of individual or collective self-defense” in response to “an armed attack” or the imminent threat thereof. Thus Poland and NATO’s ability to respond militarily is contingent on whether the Przewodów incident constitutes an “armed attack” for purposes of international law—a question that is more complicated than it may seem at first blush.
This is where intent becomes critical. While a state can be held internationally responsible in other ways for wrongful acts it commits inadvertently, an armed attack is generally understood to be a deliberate act pursued by a foreign state or other international actor. Thus, for the incident in Przewodów to trigger Poland’s inherent right to self-defense against Russia, Poland and its allies would have to find reason to believe that Russia not only caused the incident but did so intentionally or knowingly, or at a minimum acted with a high degree of recklessness.
A second important factor is the gravity of the use of force at issue. The International Court of Justice, among others, has suggested that armed attacks only include “the most grave forms of the use of force” and must be distinguished from “other less grave forms,” such as “mere frontier incident[s].” Where exactly this threshold lies is the subject of much debate and disagreement, even among NATO allies. Some states maintain that only relatively significant uses of force pass this threshold—a standard that may exclude the Przewodów incident, given its isolated nature and the relatively small number of fatalities it has caused. Other states—including the United States—argue that nearly any use of force can trigger the right to self-defense.
Regardless, in the case of the Przewodów incident, the most relevant view would be that of Poland, as only it would possess an individual right of self-defense if the Przewodów incident were found to qualify as an armed attack. Other states would only be able to respond in collective self-defense at Poland’s request, and then only to whatever extent Poland believes it has an individual right to self-defense.
If the Przewodów incident had been found to be an armed attack, then Poland would have an international legal right to respond as necessary and proportionate to address the threat posed by Russia, including with military force—and to bring in whatever allies are willing to act in collective self-defense with it to do so. What sort of response is necessary and proportionate is another issue that NATO allies sometimes disagree on, with some states (including the United States) arguing that it permits broader military responses than others. Regardless, these points of disagreement would likely be worked out by NATO members internally before any military response, so as to present as united a front as possible.
But if the incident were found not to be something short of an armed attack, then international law limits Poland and its NATO allies to diplomatic engagements, countermeasures, sanctions, and other responses that do not entail the use of military force. These themselves are nothing to be trifled with, and a focus on them should not be seen as a somehow unserious response on the part of NATO.
Poland’s membership in NATO adds another layer to this international legal analysis. Many in the public are of the mistaken understanding that NATO obligates its members—including the United States—to come to each other’s defense in the event of an armed attack. In reality, the obligations imposed by NATO membership are a bit more complicated than that.
The core obligation at the heart of the NATO Alliance is spelled out in Article 5 of the North Atlantic Treaty, which states:
[A]n armed attack against one or more [NATO members] 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, 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.
Contrary to popular belief, this does not obligate NATO members to respond militarily to an armed attack on any one of them. Instead, it merely commits them to take “such action as [they] deem necessary,” in coordination with other NATO members, where they assess an armed attack has occurred on a NATO member. Hence, even where a member state asserts its rights under Article 5, it cannot legally compel its fellow NATO members to come to its defense. This mainly serves to make clear the invoking member state’s belief that it has suffered an armed attack within the scope of the treaty, an assessment that other NATO member states may disagree with or seek to respond in a way that does not entail further military engagement. Similarly, when NATO invokes Article 5, as it did after the Sept. 11 attacks, this merely confirms that the members are unanimous that they are acting pursuant to their NATO collective defense obligations, not that they are firmly obligated to pursue a military response.
What work is then being done by Article 5’s assertion that an armed attack against one “shall be considered an attack against them all”? This arguably provides each NATO member’s advance consent to collective self-defense, expediting a potential coordinated military response. Some may even argue that this empowers NATO members to act in collective self-defense where another NATO ally who has suffered an attack does not request it or does not agree that an armed attack has occurred, though any such action would be legally questionable and highly controversial in all but the most extraordinary of circumstances.
Regardless, Poland need not make any claims under Article 5. Instead, it could rely, and in fact has relied, on another provision of the North Atlantic Treaty: Article 4, which asserts that NATO members “will consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the [member states] is threatened.” In contrast to Article 5, this language does impose a firm obligation to consult whenever a single member state asserts that it believes it is under threat. Poland invoked Article 4 just hours after the Przewodów incident, triggering the consultation among NATO members that is now scheduled for later today. A further coordinated response may yet come from that meeting, regardless of whether it concludes that Article 5 applies to the present circumstance.
As dangerous as it is, an event like the Przewodów incident does not kick off an inevitable chain of events ending in a war between Russia and NATO. International law may not even view such incidents as “armed attacks” warranting a military response. And if it does, then NATO member states have ample room to craft an appropriate response, incorporating both military and nonmilitary means. At each phase, any move toward escalation will depend on decisions made by political and military leaders.
This is why it is important that NATO states remain committed to a sober and deliberate fact-based decision-making process of the sort we’ve seen them pursue over the past 24 hours, and not give in to the understandable panic such incidents often cause among observers. What looks at first glance like a major escalation can turn out to be something less than that—a tragic accident that requires sobriety, careful diplomacy, and appropriate words of condolence, not another step toward all-out warfare.