Although it might come as a surprise to many, Russia has presented a series of legal arguments founded on international law, as made clear during Vladimir Putin’s speech at the beginning of the “special military operation”, to justify its invasion of Ukraine. It will be argued that Russia’s actions are illegal and contrary to the UN Charter, although Ukraine’s contravention of the Minsk Agreement does give Russia’s decision a degree of legal legitimacy.

Prior to proceeding with the analysis, however, it is necessary to briefly explain the prevailing international law framework in this area. The backbone of what is referred to as jus ad bellum (literally “right to war”) is formed by the United Nations Charter, which sets out the circumstances in which UN member states can justify using military action against one another. Nonetheless, this is not the only international agreement in this domain. There are both UN-derived acts (e.g., Convention on the Prevention and Punishment of the Crime of Genocide), and non-UN derived acts (e.g., Rome Statute) that are relevant to the issue. There are also certain non-universal international agreements that are relevant only to the specific conflict at hand (e.g., Minsk Agreement).

Russia’s Violation of International Law

There are two critical bases for the claim that Russia has violated international law.

The principal ground derives from Article 2(4) of the UN Charter, which states that members must:

“…refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.”

In addition to the Charter, Russia has also breached the 1994 Budapest Memorandum, which guaranteed Ukraine’s independence in exchange for the handover of its nuclear weapons stockpile to Russia, which it had inherited whilst part of the USSR. It should, however, be noted that the agreement is still subject to the UN Charter, with all of its exceptions (described beneath).

Other international agreements, such as the Rome Statute, might also be relevant, although the documents described above are more than sufficient to establish the prima facie illegality of Russia’s actions.

Self-defense

The self-defense argument is fairly straightforward – if country X intends to attack country Z, then country X has the right to take military action against country Z. This argument finds its origins in Article 51 of the UN Charter, which enshrines the right to self-defense:

 “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 formally initiated this legal defense by transmitting a notification to the UN Security Council (Document S/2022/154) immediately after the beginning of hostilities, thereby satisfying the procedural requirement contained in the second sentence.

As concerns the first sentence, two aspects are key: there must be an “armed attack”, and any military response can be individual or collective (i.e., military force can be used on behalf of another State).

It is the case that Ukraine had been increasing its level of collaboration with NATO and had more generally been increasing its military capability in the years leading up to the invasion, both through arms purchases and through the integration of previously paramilitary formations (e.g., Azov battalion) into its armed forces. Most importantly, however, NATO has expanded eastward since 1991, with the alliance increasing its military presence in the years prior to the invasion.

Nonetheless, this is where statutory construction comes into play. The aforementioned Article 51 exception is interpreted narrowly, meaning that anything save for a more-or-less direct threat (i.e., an imminent invasion) would not be sufficient to engage the clause.  Although the facts above do point towards a military build-up, nothing suggests that Ukraine or NATO had “crossed the Rubicon” and had irreversibly gone down a path of war against Russia. To be clear, international law does not require the defending country to be “hit first” – pre-emptive strikes are permitted.  But once again, even according to this looser standard, the facts on the ground, in all likelihood, do not constitute sufficient grounds for the invocation of Art. 51, at least at the individual level.

At the collective level, Russia could argue that its operations are justified in order to defend the Donetsk (DPR) and Lugansk People’s Republic (LPR), which have indeed issued formal requests for military assistance. The argument here, from a factual standpoint, appears to be stronger, as Ukraine had a substantial military presence on the borders of the DPR and LPR, with its most capable units manning what has been referred to as Ukraine’s “Maginot line” – a series of reinforced fortifications spanning roughly the area between Mariupol (in the far south) to Kramatorsk and Slavyansk (in the north). In addition to that, Ukraine has purchased substantial amounts of weaponry since 2014, and has bolstered its military capabilities since the beginning of the War in the Donbass.

The issue with this argument is not as much factual as it is legal, as the DPR and LPR are partially recognized states (merely three UN members, including Russia, recognize their independence). As recognized by the court in Paramilitary Activities, if Art. 51 had a wider definition, then it could be utilized to justify intervention whenever an opposition group requested military action, thereby opening a “Pandora’s box”. Even so, the “nail in the coffin” for this argument are the republics themselves, who despite having their own bureaucracy and military, can hardly be considered independent states. This is because they are under the de facto administration of Russia, and they have even expressed their desire of joining the Russian Federation if Ukraine is defeated.

Humanitarian intervention

Even though the DPR and LPR are not internationally recognized entities, Russia has argued that its “special military operation” is justified due to systemic human rights violations against Russians and Russian speakers in Ukraine.

There are two sides to this argument. The first concerns Russia’s allegations that the two republics have been constantly under attack by Ukrainian forces since 2014, with its officials citing a figure of 14,000 victims. Whether or not these figures are accurate is unclear. However, it is the case that Ukraine has, albeit with varying intensities, engaged in military actions against the two republics. For instance, the city of Donetsk was frequently shelled from Ukrainian positions in Avdeevka, oftentimes causing civilian deaths. The second, and often overlooked aspect of this argument is the disenfranchisement of Russians and Russian speakers outside the Donbass area. Once again, Russia alleges a systemic campaign of discrimination and terror, which includes everything from the deliberate burning alive of 39 pro-Russian demonstrators in Odessa in 2014, to laws limiting the use of the Russian language in the public sector.

The primary issue with this argument, unlike the prior one, is not factual in nature, but legal – humanitarian interventions are not a recognized category of legitimate justifications for military actions. Although the notion of humanitarian intervention has existed since at least the 17^th century, with the “father” of international law, Hugo Grotius, being the first to describe its existence, the UN Charter (as demonstrated by its legislative history and subsequent caselaw) explicitly confines the potential justifications for military action to either the aforementioned right to self-defense (Art. 51) or to a Collective Security measure under Chapter VII (i.e., UN approval).

Admittedly, the doctrine of humanitiarian intervention has been cited in the past, most recently by Russia herself during its intervention in Syria, but also in such cases as Kosovo. However, it remains highly controversial whether humanitarian intervention is a valid justification considering the significant scholarly debate on the concept, and the fact that merely two States, the UK and Belgium, have clearly stood in defense of the concept.

Therefore, even if Russia was able to prove that Ukraine’s marginalization of Russians and Russian speakers constituted genocide according to the definition set out in the Genocide Convention (which is highly unlikely), its subsequent military intervention would still lack a clear legal basis.

Minsk I and II

The Minsk agreements (hereby Minsk) were signed in 2014 and 2015, respectively, by countries of the Normandy format (Russia, Ukraine, Germany and France). These agreements sought to bring an end to the conflict in the Donbass through a package of various measures, and through ultimately reintegrating the territories of the DPR and LPR into Ukraine. Although Minsk is an internationally recognized treaty, its contravention can never constitute a justification for a full-scale invasion (explained above), but it is crucial in terms of the legitimacy of Russia’s actions. 

A full-scale analysis of all the individual instances in which the treaty was contravened would require an article of its own. Nevertheless, there is significant evidence that Kiev was obstructing the peace process through its non-implementation of certain key clauses, the most critical of which was the promise to, in exchange for their reintegration, grant Donetsk and Lugansk special status within Ukraine. Such a process would have required approval by the Verkhovna Rada, constitutional amendments, and OSCE-monitored elections, only after which would Ukraine be able to take back control of its eastern border.

Kiev plainly refused to follow through on this aspect of the agreement, citing the one-sidedness of the plan. Foreign minister Dmytro Kuleba is himself cited as saying:

“None of Ukraine’s regions will have a right to veto the state’s decisions. That is engraved in stone! Therefore, no special status as Russia is considering it, no veto right will be given.”

Admittedly, the federalization of Ukraine would have given these two regions the ability to effectively veto many critical decisions, and therefore stymie any efforts to for instance join NATO. Equally so, the agreement assumed the amnestying of ex-DPR and LPR fighters, many of which have been accused of war crimes by the government in Kiev. Although these are all valid arguments, and there is indeed evidence of the Russian side breaching the technical aspect of the agreement (e.g., ceasefires), the fact remains that Ukraine refused to implement the political aspect of Minsk. This was only bolstered by US Secretary of State Anthony Blinken’s statement only several weeks prior to the invasion, where he stated that whilst the US nominally supported the application of Minsk, the order of its implementation had to be revised, so that the demilitarization of the DPR and LPR came first, and federalization only second. In conclusion, Ukraine has clearly breached the political aspect of the Minsk agreement by refusing to implement the package of measures it had itself agreed to.

Conclusion

The three arguments analyzed above are the principal legal arguments that Russia has cited, although they are by no means the only ones. One of the critical arguments that Russian officials have frequently cited is the need for the “denazification” of Ukraine. Whether or not this is a valid argument is beside the point, as this is a non-legal justification. Another argument is the notion that Ukrainians and Russians form a “single” people, but this is once more something that goes beyond the framework of international law.

What emerges from the strictly legal arguments, however, is that, in all likelihood, Russia’s invasion is in contravention of international law. The self-defense argument, whilst nominally valid, is narrowly construed, and the threat posed by NATO is simply too abstract to justify the invocation of this ground. On the other hand, the humanitarian argument is tenuous at best, and is an argument that has generally not been recognized as a legitimate justification for the initiation of military hostilities. Nonetheless, Ukraine’s contravention of the political aspect of Minsk, whilst not enough to legally justify the invasion, does give Russia, at the very least, a degree of legitimacy for its actions.