On February 24, 2022, Russian troops invaded Ukraine, embarking on an unprovoked military aggression against an independent European country—sparking an international outcry, with countries rallying to defend Ukraine in what many describe as the biggest threat to peace and security in Europe since the end of the Cold War.
The human and financial costs have been steep, with approximately 7,000 of innocent civilians in Ukraine dead and 11,000 more injured—and millions more displaced and now living as refugees. Meanwhile, tens of thousands of soldiers have died on both sides. One year on, Ukraine has suffered tremendous losses—buildings, roads, and infrastructure destroyed, and the cost of the war escalating.
Here, Allen Weiner, an international legal scholar with expertise on international security matters, discusses the law governing the use of force, the limitations of the UN to rein in member nations, NATO support for Ukraine, the prospects of war crimes prosecutions, how this historic conflict might end, and more.
What does Russia’s invasion of Ukraine mean in terms of international law? Did Russia violate the UN charter?
It’s always interesting to teach complex, difficult, real-world questions. But if this were an international law class, I would say that Russia’s invasion of Ukraine would not be a very challenging exam question for my students because it is a quite blatant violation of Article 2(4) of the UN charter, which provides that states are not allowed to use force in their international relations. There’s a clear prohibition on the use of force under international law in the UN charter.
There are only two exceptions. One exception is self-defense, and the other exception is the use of force that is authorized pursuant to the collective security powers of the Security Council acting under Chapter VII. Neither of those is present here. There are also some other more contentious or more disputed theories under which states can claim use force under international law. But none of those would apply here, either.
What argument did the Russians use to justify the invasion?
The Russians have offered two main justifications for the use of force. One is that they somehow perceive that they were threatened by Ukraine because Ukraine might at some point join NATO and could then conceivably have nuclear weapons stationed on its territory. But the right of self-defense is available when a state has sustained an armed attack. Even if there is a right of anticipatory self-defense, which is debated, a state could use force only to ward off an imminent attack, not a threat that Ukraine some years down the road might join NATO. That’s clearly not what the right of anticipatory self-defense contemplates.
The other defense or justification the Russians have offered is that they were protecting co-ethnics, i.e., ethnic Russians in Ukraine, from genocide. There are big debates about whether states can use force to protect their nationals in a foreign country, or whether they can more generally use force to halt humanitarian abuses that are taking place in another country. But we don’t have to dig too deeply into the validity of these legal theories because there seems to simply be no factual support for the claim that ethnic Russians were being subjected to atrocities by the Ukrainian government—it simply isn’t true. And so, whether there could be a legal basis for it, if it were true, seems immaterial.
And has the UN done enough to rebuke Russia?
The UN has done really all it can, under these circumstances. After the invasion of Ukraine, the matter was immediately brought to the Security Council. The way that the Security Council is designed, the five permanent members— the United States, Russia, China, France, and the United Kingdom—have the ability to block the Security Council from taking action. And the Russians, not surprisingly, blocked the Security Council from acting.
In response to that, the case was referred to the General Assembly. The General Assembly, by a substantial majority, adopted a vote that deplored Russia’s invasion of Ukraine and demanded that Russia cease its use of force against Ukraine. The vote for that was 143 in favor and five against. (There were 35 abstentions, which is interesting.) But decisions of the General Assembly are essentially seen as recommendations; they have no legally binding force of the same kind that decisions of the Security Council would have. We’ve also seen other decisions by international bodies. Ukraine brought a lawsuit in the International Court of Justice. Although that case only been through its earliest stage, the so-called provisional measure stage, the court adopted a quite clear decision demanding that Russia suspend its military operations. Of course, Russia disregarded both the decision of the General Assembly and the order of the International Court of Justice.
Does this highlight the limitations of the UN, that a country can violate the charter of the UN and still have such power?
We have to assess that question in light of the underlying structure of the international legal system. International law, unlike domestic legal systems, is largely a consent-based system. There’s not a world government, there’s not a world police force. It is a system of cooperative exchanges of commitments. And when the main instrument for international security, the UN Charter, was adopted, it was built with a particular power structure in mind, namely, the assumption that the five states that had won World War II and had defeated the Axis powers, Japan and Germany, would remain aligned as forces to suppress aggression of the kind that Japan and Germany had perpetrated. And the UN Charter provides those five states – the permanent members of the Security Council – with a guarantee that the U.N. Charter’s collective security system won’t be turned against them. That is the so-called veto mechanism, which means that binding resolutions of the Security Council require the concurring votes of the permanent members.
This obviously means that actions by the permanent members or their close allies are not going to be subjected to the collective security mechanisms of the Security Council. Now, the United States does not necessarily oppose this arrangement. The United States itself exercised its veto power to block a Security Council resolution condemning the 1989 United States invasion of Panama. We have also used the veto when the Security Council has sought to condemn American allies, in particular Israel. So, the UN charter system is one that basically is limited when the core interests of the great powers or their close allies are implicated, and we clearly see the limits of how the United Nations can operate. But, that is based on the system that we designed so we now live with the consequences.
Is the Rule of Law weakened now?
As an international law professor, I point out that even though the law was flagrantly violated in this case, international law has nevertheless been important. I think the sense that what Russia has done is not only antithetical to our interests, but is a shocking violation of legal norms and values that we care about, has contributed to the strong international response to Russia’s invasion.
Countries in Latin America voted to condemn Russia’s invasion of Ukraine. They did not do so for fear that Russia might invade them. The strong condemnation of Russia in the General Assembly was not simply a geopolitical calculation of interests. International law, and the way that Russia has endangered it, has been a powerful force in terms of helping to unify political support and institutional responses to Ukraine’s invasion. So sometimes even when the law is broken, it can assert its power in a decentralized system like the international system. International law has been a powerful source of motivation for the behavior of states and has contributed to the emphatic response to Russia’s invasion and the very intense support for Ukraine that we observe.
How effective have sanctions been?
There’s a debate among experts about the effects of these sanctions. One of the problems is that the most severe sanctions that could have been adopted, which would be a complete ban on Russian energy exports, are not possible because of the dependence of Western Europe on Russian energy, particularly natural gas exports. And so even during the past year, Russia has continued to earn substantial foreign exchange through the export of energy, including in some cases to those countries that are most deeply opposed to Russia’s invasion of Ukraine.
But sanctions are having an effect. Technology in particular is an area in which Russia is beginning to face real pressure with respect to its ability to get items, in particular semiconductor chips, necessary for infrastructure that depends on advanced technology. Russian GDP has fallen and its debt has increased. But Russia is a personalist dictatorship, where the fact that the population may be suffering from economic dislocation is not enough to cause the government to change from its path, at least in the short term. The effect of sanctions will have to be measured over the longer term.
Can you foresee any rationale for NATO doing more?
Well, I think NATO has done a great deal in terms of providing financial, material assistance, and training assistance to Ukraine. One of the things that’s interesting about the conflict taking place in Ukraine is that the United States and its NATO allies had, for decades, prepared for the possibility of a conventional invasion of Western Europe by the old Soviet Union. The expectation was that NATO forces would face a dramatically superior conventional force in terms of numbers. The training and the tactics that NATO states developed accordingly focused on the use of light units that would be highly mobile; this was how NATO tactically planned to confront a superior ground force without engaging in a frontal assault. That’s exactly what NATO trained Ukrainian troops to do in the run up to this invasion. And it’s exactly what they did to forestall Russia’s attempt to capture the capital, Kyiv NATO training, along with the weapons NATO states have supplied, have been essential for the success of Ukraine’s defense.
Now, does NATO actually want to engage in active armed conflict with Russia? Do NATO states want to do what the United States and other countries did in Kuwait in 1990, i.e., to actually go to war with the aggressor to expel Russia from Ukraine, as we sought to expel Iraq from Kuwait? No. NATO clearly has no interest or desire to do that, simply because the risk of armed conflict with one of the two largest nuclear powers in the world creates unacceptable risks of escalation.
The death toll on both sides, for Ukrainian and Russia, has been high. But it has been reported that there has also been an exodus from Russia of men avoiding the draft. How do you think this may impact the war?
That’s correct. Recall that the invasion started as a so-called special military operation, which was expected to be a lightning swift operation that would bring this government in Kyiv to its knees. But it has turned into a long, stalemated, and bloody war. As a result, Russia has had to mobilize, i.e., to conscript, significant numbers of Russian men. In response, we saw substantial numbers of Russians leave the country, heading for Turkey, the central Asian republics, and elsewhere. And we’ve seen tremendous suffering. We read reports about those Russian conscripts being sent to the front lines without adequate training and equipment—as kind of human waves in some of these infantry battles. The human loss in this war has been terrible on both sides. But the Russian military, for its part, seems to be willing to accept the mass slaughter of Russian troops in the hopes of overwhelming Ukrainian positions.
We nevertheless continue to see, to the extent that we can, quite significant levels of support for both President Putin and for the so-called special military operation in Russia. This is in part because the media is very heavily controlled by the Russian government. And the state media itself is pushing out a very, very consistent state line. But there seems to be a significant generational divide in public opinion. Younger people in Russia who have more access to alternative sources of media are much less supportive. But the older generation of Russians, who get their information mainly from watching television where state media control is most intense, are much more sympathetic to the messages that President Putin tells about this struggle being a continuation of the Great War, Russia’s struggle against Nazi Germany and World War II.
Do you think criminal prosecution of Putin or any of his officials is possible at the ICC?
The criminal law situation is complicated. The International Criminal Court has jurisdiction over some of the crimes that have been committed in Ukraine because Ukraine has made declarations consenting to the jurisdiction of the ICC (even though Ukraine is not a party to the Rome Statute, the treaty that created the ICC). As a result, the ICC has jurisdiction over any war crimes, crimes against humanity, or acts of genocide committed in Ukraine. But because of the idiosyncratic structure of the Rome Statute, and because Russia is not a party to the Rome Statute, the court is not able to exercise jurisdiction over the crime of aggression—the launching of an illegal war—perpetrated by Putin or other Russian leaders. I can envision Russian soldiers and Russian commanders being charged with war crimes and possibly crimes against humanity. There is quite extensive evidence of atrocities having been committed by Russian forces in Ukraine. Whether or not it would be possible to indict Putin would depend on whether there was evidence that he directed his forces to commit war crimes and whether he was in control of those specific operations. That can be difficult to do as an evidentiary manner. You need to know not only that Putin was the commander-in-chief of the Russian armed forces, but that he gave specific orders or had operational control or direction over specific operations.
So, I expect to see prosecutions or at least indictments against Russian officials, including Russian soldiers, Russian military commanders, and perhaps senior civilian officials in the Ministry of Defense.
Could war crimes prosecutions happen in other jurisdictions?
There could also be prosecutions, or at least indictments, in domestic courts in various countries. We’ve already seen Russian soldiers captured in Ukraine tried and convicted of war crimes in Ukrainian courts. And theoretically, we could see prosecutions under domestic Ukrainian law for the crime of aggression because there is a crime of aggression under domestic Ukrainian law going back to the post-World War II era. In response to the aggression Ukraine sustained at the hands of the Nazi German regime, they enacted a law-making aggression a crime under Ukrainian law.
You could also see prosecutions for war crimes in the domestic courts of other countries in Europe that have laws providing for universal jurisdiction over such offenses. Germany, the Netherlands, and a number of other countries have war crime statutes that make it a crime to commit these offenses, whether or not the offense occurred on their territory. So, there are a number of fora that potentially have jurisdiction—Ukrainian courts, European courts, and the International Criminal Court.
Whether Putin or other senior Russia leaders actually end up ever being tried involves the separate issue of whether or not these courts would be able to gain custody over such defendants. In the case of the Ukrainian prosecutions, the Russian soldiers who’ve been prosecuted were prisoners who were captured on Ukrainian territory in the context of the ongoing fighting.
I don’t expect the Minister of Defense of Russia or Vladimir Putin or other senior Russian leaders to be captured on the battlefield. If the ICC or a national court were to initiate an indictment against them, they would then have to request the surrender of those individuals. While the current regime is in power in Russia, I don’t expect that to happen.
So it’s unlikely that Putin will be held responsible?
It certainly seems unlikely now, but my experience is that sometimes things we believe are impossible can become possible. When I served as the Legal Counselor at the U.S. Embassy in The Hague and we were working very closely with the Yugoslavia War Crimes Tribunal. The Tribunal had indicted Slobodan Milošević, the President of Serbia, for atrocities committed in the wars in both Kosovo and in Bosnia. But he was the president, he was the head of state of the Federal Republic of Yugoslavia. And the idea that Milošević would ever turn himself over to the ICTY was fanciful—it seemed ridiculous.
But circumstances changed, and Milošević fell from power. And I was in my position in the Embassy in 2001 and helped to arrange the transfer of Milošević from Serbia to Bosnia to the Netherlands, where he was brought into custody and was put on trial. Justice was not done in that case, because Milošević committed suicide before his trial finished. But the point is that there is no statute of limitations on these kinds of crimes. And so, do I expect to see Vladimir Putin in the dock today? No. Tomorrow? No. In three years? No. At some point? Well, perhaps.
How do you think this will end?
Not long after this began, that question came up. At the time, I thought we were looking at what was likely to be a very, very long stalemate. That was based in part on the fact that a stalemated armed conflict had already been for eight years. Russia and Ukraine have been fighting in the Donbas since 2014, since Russia’s original invasion of Ukraine, which was initially carried out by troops not wearing Russian uniforms. Between 2014 and 2022, we have witnessed a really bloody stalemate. And what we see now is a bloody stalemate at a much, much more intensified level of bloodshed.
I believe that political support in the West for Ukraine will remain firm. The Europeans will have made it through this winter, which is really critical with respect to energy supplies. Energy was the one real point of leverage that the Russians had to push the Europeans to maybe pressure the Ukrainians to explore a negotiated settlement.
But the Europeans will continue to make significant progress in terms of expanding alternative sources of energy, which means their dependence on Russian natural gas will decline. And so I don’t anticipate any diplomatic or political pressure on Ukraine from Europe to pursue a negotiated settlement. We’ll have to watch what happens in the American Congress now that the Republicans control the House of Representatives. There may be some who have more of an isolationist stance and maybe are unhappy with the amount of money that’s being spent to support Ukraine. So, we have to watch to see how this will play out. But I think it’s likely that domestic political support in the United States for Ukraine’s efforts, which will bring with it the ability to continue resupplying Ukraine militarily, will continue.
On the battlefield, I think we will see Russia push to expand its control of territory in the Donbas, relying on overwhelming numbers of manpower. There may be a limit to how long that tactic is sustainable. The next couple of weeks could be really critical for Ukrainian forces as they try to hold their ground. So, while I continue to think that the likeliest scenario is that this stalemate continues for a long time with small changes in control of ground on the battlefield, there is another scenario. It is possible that Russian forces may find themselves depleted, both in terms of manpower and munitions. We read stories about how these two sides are expending ammunition, artillery shells, and missiles at a staggering rate. And I do believe that the West collectively has more ability to replenish Ukraine’s supplies than Russia has to replenish its supplies. If Russia exhausts its manpower and munitions supplied, we could see the possibility of a collapse of Russian forces on the front lines. That could see dramatic advances by Ukrainian forces of the kind that we saw a few months ago when they retook significant portions of territory.
So those seem to me to be the two likeliest scenarios. Above all, I hope that Russia does not at any point perceive that its back is sufficiently pressed against the wall and it feels the need to do something extremely dangerous, like the use of tactical nuclear weapons. And there’s no real battlefield reason to use such weapons. It would be something that the Russians might do to signify their political determination and political resolve. If that were to happen, we would be entering into a very, very dangerous and risky situation. I think the Russians themselves probably recognize the risks, which means I hope would be disinclined to pursue any use of nuclear weapons.
Thank you very much, Allen.
Allen S. Weiner is an international legal scholar with expertise in such wide-ranging fields as international and national security law, the law of war, international conflict resolution, and international criminal law (including transitional justice). His scholarship focuses on international law and the response to the contemporary security threats of international terrorism, the proliferation of weapons of mass destruction, and situations of widespread humanitarian atrocities. He also explores assertions by states of “war powers” under international law, domestic law, and just war theory in the context of asymmetric armed conflicts between states and nonstate armed groups and the response to terrorism. He is a senior lecturer in law at Stanford Law School and director of the Stanford Program in International and Comparative Law and the Stanford Center on International Conflict and Negotiation.