Russia’s “Special Military Operation” and the (Claimed) Right of Self-Defense


| Feb 28, 2022

Russia's Self-Defense Claim

On 24 February, Russia attacked Ukraine on several fronts. Two days earlier, President Vladimir Putin had announced Russia’s recognition of Luhansk and Donetsk People’s Republics in the Donbas region and ordered in so-called “peacekeepers.” Those breakaway entities had declared independence from Ukraine following Russia’s 2014 invasion of Crimea, Crimea’s subsequent declaration of independence, and its annexation by Russia.

The day Russia launched its operations, its Permanent Representative to the United Nations notified the UN Secretary-General that the military action was “taken in accordance with Article 51 of the UN Charter in the exercise of the right of self-defence.” In explanation, he simply appended a speech Putin had made to the Russian population earlier in the day announcing the commencement of the campaign. The Russian Representative then transmitted the notification to the Security Council (UN Doc. S/2022/154). In turn, the Council voted 11-1 to condemn the Russian action, with China, India and United Arab Emirates abstaining. Russia’s vote against as a Permanent Five member killed the proposed resolution.

In this article, I examine the Russian claim that it is acting in self-defense. If it is not, the Russian attack violates UN Charter Article 2(4) and the customary international law prohibition on the use of force. It thus qualifies as an “internationally wrongful act” under the law of State responsibility.

The Background

Understanding the legal character of the current hostilities requires an understanding of how Russia and Ukraine arrived at this point. The trigger was Crimea. Since the break-up of the Soviet Union, the status of Crimea (and other areas scattered across the former Soviet space) has been contentious.  In part, this is because Crimea was part of the Russian Soviet Federative Socialist Republic prior to being incorporated into the Ukrainian Soviet Socialist Republic in 1954. Eventually, Russia and Ukraine agreed to “respect each other’s territorial integrity, and confirm the inviolability of the borders between them” in the 1997 Treaty on Friendship, Cooperation and Partnership.

Despite the treaty, tension between the countries persisted, as it did within Ukraine between those who looked westward towards European and NATO integration and others who saw ties with Russia as preferable. In 2014, protests (the “Euromaidan” protests) broke out in Ukraine when, under pressure from Moscow, then-President Viktor Yanukovych backed away from signing an “Association Agreement” with the European Union. Despite the government’s brutal crackdown, Yanukovych had to flee the country to Russia. Ukraine’s legislature, the Verkhovna Rada, replaced him temporarily until elections could be held.

Concerned that it might lose access to its Black Sea Fleet base on the Crimean Peninsula (among other reasons), Russia quickly occupied Crimea, which issued its Declaration of Independence of the Autonomous Republic of Crimea and Sevastopol in March. The same month, nearly 97% of the population supposedly voted for annexation by Russia in a referendum. Russia promptly approved annexation. This action was, and remains, condemned throughout the international community (e.g., UN, EU).

Meanwhile, Russia continued its subversion of Ukraine in the Donbas region. Donbas is populated primarily by ethnic Russians. Pro-Russian demonstrations grew into open hostilities between armed separatist groups and government forces, with Luhansk and Donetsk declaring independence in April. As the conflict escalated, Russia moved from providing materiel and volunteers to direct military involvement.

The parties agreed to a ceasefire in September (Minsk I), but quickly violated it. In February 2015,  Ukraine, Russia, France, Germany, and the separatist groups negotiated a new agreement, Minsk II. It provided for a ceasefire, withdrawal of heavy weapons from a security zone, OSCE monitoring and verification, and dialogue about autonomy for the Donbas entities. However, arguments persisted over execution of the agreement, and the situation soon became yet another “frozen conflict” in the post-Soviet space, like those in Moldova and Georgia. Sporadic exchanges of fire became the norm, accompanied by dozens of hasty ceasefires. Obviously, the present Russian military action sounded the death knell for Minsk II and its progeny.

Importantly, throughout the crisis, Putin has repeatedly claimed that Ukraine and Russia are one people with a “shared destiny,” a claim made to President George W. Bush as early as 2008. Most ominously, in his July 2021 essay, “On the Historical Unity of Russians and Ukrainians,” Putin argued that no separate Ukrainian nation existed before the creation of the Soviet Union.

Putin’s Article 51 Claims

Article 51 of the UN Charter provides

Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.

Russia’s notification complies with the requirement that actions in self-defense be reported promptly to the Security Council. Therefore, the issue is whether the Russian military campaign is a lawful exercise of self-defense pursuant to the first sentence, which reflects customary international law. In this regard, two points are key. First, the condition precedent to the exercise of self-defense is an “armed attack.” Second, the use of force in response to that armed attack may be individual or collective. The latter may be exercised in collaboration with the victim State or entirely on behalf of that State.

The Putin Speech

Putin’s speech is the key to understanding the nature of Russia’s Article 51 claim. He begins by pointing to “the fundamental threats which irresponsible Western politicians created for Russia consistently, rudely and unceremoniously from year to year. I am referring to the eastward expansion of NATO, which is moving its military infrastructure ever closer to the Russian border.”

To illustrate the threat this poses, he cites NATO and U.S. operations against the Federal Republic of Yugoslavia, Iraq, Libya, and Syria, all of which, he argues, were contrary to international law. And as to NATO expansion, Putin claims “they have deceived us, or, to put it simply, they have played us.”

Looking forward, Putin asks, “[W]hat next, what are we to expect? If history is any guide, we know that in 1940 and early 1941 the Soviet Union went to great lengths to prevent war or at least delay its outbreak…. When it finally acted it was too late.” And then he comes to the crux of Russia’s legal claim.

Even now, with NATO’s eastward expansion the situation for Russia has been becoming worse and more dangerous by the year. Moreover, these past days NATO leadership has been blunt in its statements that they need to accelerate and step up efforts to bring the alliances infrastructure closer to Russia’s borders…. We cannot stay idle and passively observe these developments. This would be an absolutely impossible thing for us to do.

Of course, the question is not about NATO itself…. The problem is that in territories adjacent to Russia, which I have to note is our historical land, a hostile “anti-Russia” is taking shape. Fully controlled from the outside, it is doing everything to attract NATO armed forces and obtain cutting edge weapons.

They will undoubtedly try to bring war to Crimea just as they have done in Donbass, to kill innocent people just as members of the punitive units of Ukrainian nationalist and Hitler’s accomplices did during the great patriotic war. They have openly laid claim to several other Russian regions.

They did not leave us any other option for defending Russia and our people, other than the one we are forced to use today.

Yet, for Putin, the threat is not just to Russia.

This brings me to the situation in Donbass…. [Y]ou cannot look without compassion at what is happening there. It became impossible to tolerate it. We had to stop that atrocity, that genocide of millions of people who lived there and who pinned their hopes on Russia, on all of us.

In these circumstances, we have to take bold and immediate action. The people’s republics of Donbass have asked Russia for help.

Finally, Putin cites Article 51 and the treaties of friendship and mutual assistance that had just been signed with the Donetsk and Luhansk People’s Republic as the basis of Russian action. For Putin, self-defense required a so-called “special military operation” to “demilitarize and denazify Ukraine, as well as bring to trial those who perpetuated numerous bloody crimes against civilians, including against citizens of the Russian Federation.

Individual Self-defense

The primary basis outlined in the Putin speech for Russia’s military action is individual self-defense by Russia against the United States and NATO. As those countries have not launched military operations, it is a claim of the right to “anticipatory self-defense.”

Anticipatory self-defense has long been a fraught issue in international law. From the various positions that have been set forth by States and scholars, three general approaches emerge. By the first, the text of Article 51 is clear; there is no right to act in anticipation of an armed attack; the attack must be underway.

Yoram Dinstein explains this position in his classic War, Aggression and Self-Defence. For him, the right of self-defense only arises once the armed attack has been launched, although he hastens to add that the first shot need not have been fired. Rather, the right of “interceptive self-defence” attaches once an adversary has embarked “upon an apparently irreversible course of action, thereby crossing the legal Rubicon.” By this standard, the Russian claim fails, for there is no evidence that any planned NATO military operation had begun at the time Russian forces began their assault.

The more traditional approach to self-defense allows for forcible defensive action in the face of an “imminent” armed attack. The 2002 U.S. National Security Strategy, which argued for a new approach to imminency, described this view.

For centuries, international law recognized that nations need not suffer an attack before they can lawfully take action to defend themselves against forces that present an imminent danger of attack. Legal scholars and international jurists often conditioned the legitimacy of preemption on the existence of an imminent threat-most often a visible mobilization of armies, navies, and air forces preparing to attack.

In other words, the enemy must be at the gates in a tangible sense. The “indications and warnings” of imminency in this sense are precisely the sort of activities Russian forces were conducting in Russia, Belarus, and the Black Sea.

But again, the United States and NATO were engaged in no activities that would have enabled them to attack Russia on short notice. Even the NATO defensive actions cannot be characterized as such; the limited deployment of forces into the region and on the Russian border did not give NATO a meaningful offensive capability against Russia’s forces. Indeed, it is questionable whether they provided any defensive capability beyond ensuring that NATO would enter the fray if the Russians crossed the border.

Finally, with the 2002 National Security Strategy, a new approach to anticipatory self-defense emerged, one gaining increasing traction. By it, States may act when the “last window of opportunity” to defend itself is about to close. Writing about the approach before its eventual adoption by the United States (see, e.g., here) and other States (e.g., Australia), I explained,

[I]t would be absurd to suggest that international law requires a State to “take the first hit” when it could effectively defend itself by acting preemptively. This being so, the correct standard for evaluating a preemptive operation must be whether or not it occurred during the last possible window of opportunity in the face of an attack that was almost certainly going to occur. Restated, it is appropriate and legal to employ force preemptively when the potential victim must immediately act to defend itself in a meaningful way and the potential aggressor has irrevocably committed itself to attack. This standard combines an exhaustion of remedies component with a requirement for a very high reasonable expectation of future attacks – an expectation that is much more than merely speculative.

The Russian position falters even by this more relaxed standard of anticipatory self-defense (sometimes unfortunately labeled “preemptive self-defense”). The last window of opportunity can only present itself when the other side has decided to attack, and a failure to act might forfeit the chance to mount an effective defense. There is no indication that NATO had decided to attack Russia.

This is so even if Crimea is considered part of Russia, which, as a matter of law, it is not (see Geiss). There is no indication that NATO, or even Ukraine, had decided to mount an attack to retake Crimea. Moreover, had they so decided, the forces in place to do so effectively were not in place; thus, there was no last window of opportunity. On the contrary, Russia and the West were engaged in a series of negotiations over the situation, throughout which Russia enjoyed the upper hand militarily.

This means that Russia’s actions are at best an example of “preventive self-defense,” at worst, and most accurately, pure aggression. Preventive self-defense occurs when one of the three essential elements of the last window approach is missing: 1) capability to mount an armed attack; 2) a decision to launch an armed attack; and 3) the need to act now lest the opportunity to effectively defend oneself be lost. Preventive self-defense employs force to deprive an adversary of its future ability to mount an armed attack (which the Russians are successfully doing) in a situation that does not allow anticipatory self-defense. Such actions are unlawful. They can, and usually would, qualify as an armed attack giving the targeted State its own right of self-defense, and the corresponding right to look to other States for military assistance in collective self-defense.

Collective Defense

Although Putin’s speech spoke of genocide, which suggests a justification on the highly controversial basis of humanitarian intervention, Putin has elected instead to style the Russian operations as collective defense of the Luhansk and Donetsk People’s Republics, with which Russia has freshly minted mutual military assistance treaties. In this regard, the existence of the agreements is of little legal significance vis-à-vis collective defense, for military assistance may be provided by another State based on an ad hoc request. As Putin noted, the two so-called republics have requested Russian assistance, thereby satisfying the requirement of request noted by the International Court of Justice in the Paramilitary Activities judgment (para. 199).

The problem for Putin is that the right to request military action in self-defense (or intervention of military forces more broadly, as in the case of assistance in fighting an insurgency) is limited to States. In Paramilitary Activities (para. 246), the Court emphasized this point: “[T]he principle of non-intervention derives from customary international law. It would certainly lose its effectiveness as a principle of law if intervention were to be justified by a mere request for assistance made by an opposition group in another State.”

Non-State groups may get assistance on the basis of humanitarian intervention (but only if such a right even exists in international law, as the United Kingdom urges it does) or pursuant to a Chapter VII authorization by the UN Security Council. Support for insurgent groups in other than those cases is an unlawful intervention into the internal affairs of another State (Paramilitary Activities, paras. 202-205, 251), a topic to be addressed by other contributors to this forum.

One hurdle Putin does not have to cross is the timing of the action. Although Russia has just formally recognized the two entities as States, this does not necessarily mean that they did not qualify before the date of recognition (although, as a matter of law, they did not). Thus, Putin could point (incorrectly) to the ongoing hostilities stretching back to 2014 as the “armed attack” against which the collective defense is provided. And as to the Minsk II and other ceasefire agreements, Putin has claimed they “were killed long before yesterday’s recognition of the people’s republics of Donbas…And not by us, not by representatives of these republics, but by the current Kyiv authorities.” When one party materially breaches a ceasefire agreement, the other side is entitled to resume fighting if it so chooses. The Russian claim would be counter-factual, but there is at least a chain of legal logic to get to the point where the current operation is claimed collective defense supporting the right of the two entities to self-defense.

The fatal flaw in the Russian argument is the status of Luhansk and Donetsk. The question is whether they are States. The international community overwhelmingly considers them part of Ukraine. But in terms of satisfaction of the criteria for Statehood, they fail on the basis of the “independence” criterion. As the late James Crawford has observed, the Statehood of entities created through an unlawful use of force is doubtful. This is especially the case when the entity is “dependent upon its foreign sponsor” because that brings into question the Statehood condition precedent of independence, which Crawford labels as “the central criterion.”

Crawford does admit that it is sometimes the case that “military intervention, for the purpose of supporting the right to self-determination, particularly in the context of decolonization, has been accepted in practice.” However, he hastens to add that such cases are “not without misgivings.” But the principle of self-determination codified in, inter alia, Article 1(2) of the UN Charter is hard to apply in the Donbas. Recall Putin’s repeated claims about the lack of cultural and other distinctions between Ukrainians and Russians. The right of self-determination only attaches to a distinct “people.” Whatever that term might imply (an unsettled contentious issue), Putin’s statements asserting that Ukrainians and Russians are a single “people” undercut its application in this case.

Furthermore, in its 2010 advisory opinion on Kosovo’s declaration of independence (para. 81), the International Court of Justice likewise zeroed in on whether the purported State in question is the product of the unlawful use of force.

[T]the illegality attached to the declarations of independence thus stemmed not from the unilateral character of these declarations as such, but from the fact that they were, or would have been, connected with the unlawful use of force or other egregious violations of norms of general international law, in particular those of a peremptory character (jus cogens).

Factually, it is clear that but for Russia’s unlawful use of force in Crimea and the support it subsequently gave insurgents in the Donbas, the Luhansk and Donetsk People’s Republics would not exist today.

Finally, even if the two entities had qualified as States, the Russian action in collective self-defense failed to satisfy the two universally accepted criteria of self-defense, necessity and proportionality (see, e.g., Paramilitary Activities, paras. 194, 237; Nuclear Weapons, para. 41; Oil Platforms, paras. 43, 73-74, 76). The necessity criterion requires that forcible action be needed to defend the State facing the armed attack. Yet, active negotiations were underway, and there is no indication that the defensive situation was worsening from the perspective of the two entities. On the contrary, Russian peacekeepers had entered the area, thereby lowering the supposed threat they faced from Ukraine.

As importantly, the scale and scope of the Russian military action far exceed that required to defend the so-called Luhansk and Donetsk People’s Republics. Even if the presence of the Russian “peacekeepers” provided an insufficient shield from Ukrainian attack or the People’s Republics were acting in self-defense to seize back territory “unlawfully” held by Ukrainian forces, there would have been no reason to attack into Kiev and other regions of Ukraine.


The Russian justification for military action against Ukraine is without any basis in international law. As I have discussed earlier in Articles of War, the Russian military attack is merely the continuation of an unlawful use of force against Ukraine that began in 2014. Although the Minsk agreements and subsequent ceasefires may have temporarily suspended hostilities, Ukraine’s right of self-defense remained intact. And in any event, Putin acknowledges those agreements are a dead letter.

Therefore, even if false Russian claims of a threat from NATO and/or Ukraine are taken at face value, Ukraine enjoyed a legal right to expel Russian troops from its territory. Such an exercise of self-defense could only qualify as an armed attack if it was disproportionate or unnecessary. Moreover, as Ukrainian territory, it would be lawful for Ukraine to forcibly exert control over the territory controlled by insurgents in the Donbas and ask other States for help in doing so.

And finally, even if NATO is a hostile offensive alliance looming on the borders of Russia (which it is not), any Russian right to self-defense had not yet matured. The Russian attack is quite simply an act of aggression and use of force, an egregious violation of international law.


Michael N. Schmitt is the G. Norman Lieber Distinguished Scholar at the United States Military Academy. He is also Professor of Public International Law at the University of Reading, Strauss Center Distinguished Scholar and Visiting Professor of Law at the University of Texas, and Professor Emeritus at the United States Naval War College.


Photo credit: Zack Lee via Flickr