A Russian invasion of Ukraine would be an international crime

As clamours for war reach a fever pitch, there has been much discussion of how the West might retaliate against Russia should it invade Ukraine. Most suggestions have focused on the imposition of sanctions, such as freezing Russia out of the international financial system and rendering it an economic pariah. The language used is almost exclusively the realist one of a geopolitical contest between a resurgent Russia and an increasingly defensive West – and how the latter might deter the former.

As international lawyers, we note and deplore that the international legal framework governing the use of force is conspicuously absent from public discourse about Russia’s potential invasion.

When it invaded Crimea and Eastern Ukraine in 2014, Russia attempted to avoid claims that it was unlawfully resorting to force by sending its soldiers – the “little green men” – across the border wearing unmarked uniforms. Now, Russia is openly massing its military resources on the Ukrainian border, claiming that any incursion into Ukrainian territory would be a justifiable reaction to NATO’s seemingly inexorable expansion eastward.

Conversely, although it occasionally tips its hat to the need for the United Nations to maintain international peace and security in the region, the West primarily frames Ukraine’s standoff with Russia in terms of maintaining the balance of power in Europe and ensuring the continuity of European energy supplies. On both sides, then, the language is unmistakably that of political calculation and opportunity.

What is missing from this representation is a strong sense that an invasion of Ukraine would explicitly violate one of the most cherished and central norms of international law: the prohibition of aggression. Article 3 of Resolution 3314, adopted without a vote by the UN General Assembly in 1974, defines aggression as “[t]he invasion or attack by the armed forces of a State of the territory of another State, or any military occupation, however temporary, resulting from such invasion or attack, or any annexation by the use of force of the territory of another State or part thereof”.

By this standard, there is no question that a Russian invasion of Ukraine would be an illegal act of aggression and would trigger the full responsibility of Russia as a state for all its consequences. Such aggression would not only violate the sovereignty of Ukraine, but it would also be an assault on the peace and security of the international community. And most importantly, it would violate the rights of the countless human beings on both sides of the conflict who would inevitably be harmed by it.

But that is not all. Since World War II, the international community has recognised that aggression is an international crime when committed by high-ranking military or government officials. Twelve of the 24 defendants in the Nuremberg trials were convicted of the crime of aggression, then known as crimes against peace, receiving sentences ranging from 10 years’ imprisonment to death.

More recently, the International Criminal Court’s 123 member states adopted a series of amendments to the Rome Statute defining aggression and activating the court’s jurisdiction over the crime.

We are certainly not naïve about the efficacy of that prohibition. Including the crime of aggression in the Rome Statute was a contentious process, one that resulted in a very limited jurisdictional regime. Most relevantly, the crime does not apply to aggressive acts committed by countries that have not joined the ICC.

The court would thus be unable to prosecute Russian officials responsible for an invasion of Ukraine because Russia is not an ICC member state. However, it could conceivably prosecute war crimes committed therein, as it is considering doing in relation to Russia’s invasion of Crimea and Eastern Ukraine, a situation for which Kyiv has already accepted ICC jurisdiction.

The ICC, however, is not the only game in town. More than 40 countries have criminalised aggression domestically, a handful of which exercise universal jurisdiction over the crime and can thus prosecute it no matter where or by whom it is committed.

One country that criminalises aggression is, in fact, Ukraine itself. It applied that provision in the aftermath of Russia’s invasion of Crimea and Eastern Ukraine, convicting former President Viktor Yanukovich in absentia for complicity in aggression and two former Russian soldiers for taking part in the illegal invasion. Yanukovich was sentenced to 13 years’ imprisonment; the Russian soldiers, 14 years each.

It is unlikely that the threat of Ukraine or a third country prosecuting a Russian military or governmental official for aggression would be enough to convince Russia not to invade Ukraine. Nevertheless, a well-timed and carefully formulated warning concerning the possibility of prosecution could have at least a marginal deterrent effect – if not on Russian President Vladimir Putin himself, perhaps on some individual officials within Russia’s top brass more sensitive to international condemnation.

Highlighting the potential criminality of invading Ukraine would also foreground the idea that, by resisting Russian aggression, Ukraine would be exercising its inherent right of self-defence under international law. Such framing might, in turn, encourage third states to play a more active role in helping Ukraine defend itself – even if their assistance falls short of directly intervening on Ukraine’s behalf. It would also, if an invasion did occur, caution third states against any temptation to recognise that illegal situation, condemning a Russian-occupied Ukraine to international isolation.

The time to act is now. The significance of international law is not only in how it leads to punishment but also in how it prevents violations in the first place. We should not wait for Russia to commit aggression against Ukraine. Some authority – whether the ICC or Ukraine or even the UN General Assembly – should clearly and publicly remind Russia that, whether anyone gets prosecuted for it or not, an act of aggression is a grave violation of and a crime under international law.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.