Oleksandr Marusiak is a lawyer and international law expert, currently a senior research fellow at the Comparative Law Department of the Research Institute of State Building and Local Self-Government at the National Academy of Legal Sciences of Ukraine. He spoke to The Ukrainian Week about the legal mechanics behind so-called “territorial exchanges” between Ukraine and Russia, the potential fallout if Western countries recognise Russia’s claims to Crimea, and the realistic prospects for reclaiming occupied territories through diplomacy.
— In the so-called “peace plans,” there’s a recurring formula: Ukraine does not legally recognise the occupation of its territories, but accepts Russia’s de facto control over them for an indefinite period. How does that align with Article 73 of the Ukrainian Constitution, which requires any territorial changes to be approved by a nationwide referendum?
— First, it’s important to set the frame for this entire discussion: the war between Russia and Ukraine isn’t really about territory.
It’s about Ukraine’s very existence as an independent state. No territorial concession can satisfy Putin, because the idea of a Ukraine he cannot control is unacceptable to him. Any serious analysis has to start from that reality.
Now, let’s start with the basics. People often confuse the territory a state legally claims—its official borders, or what we can call its “legal territory”—with the land it actually controls. Ideally, a state’s legal territory should be clearly defined, undisputed, and fully under the authority of its government. In practice, though, the situation is often much more complicated.
In Ukraine’s case, its legal territory is defined by the Constitution and international treaties—basically, the borders that existed before Russia annexed Crimea in March 2014. But because of Russian aggression, not all of that legal territory is actually under the control of Ukraine’s authorities or Armed Forces.
Article 73 of the Constitution deals with legitimate changes to Ukraine’s legal territory, not the day-to-day realities of who controls what on the ground. According to the Constitution and the Law “On the All-Ukrainian Referendum,” any lawful change to Ukraine’s territory can only happen if an international treaty on the matter—already concluded and ratified by the Verkhovna Rada—is approved by a nationwide referendum. There’s still debate in legal circles over exactly what this constitutional provision covers: does it apply only to gaining territory, or to any kind of territorial adjustment? One thing is clear: a referendum isn’t just about discussing the idea of changing Ukraine’s borders. It must involve a fully ratified international treaty, and it’s organised by the Verkhovna Rada itself.
From the perspective of Ukrainian law and international law, the territories currently under Russia’s de facto control—regardless of the fact that some were unlawfully “annexed”—are still considered occupied territories under Ukraine’s jurisdiction. It’s crucial to understand that Russia’s control over these areas doesn’t automatically give it sovereignty. For them to be legally recognised as Russian, the due legal process is required—the very one we just discussed.
Without a new international treaty on changing the Ukrainian–Russian border, ratified and approved, Ukraine’s territory remains the same as defined by the 2003 Treaty between Ukraine and Russia on the state border.
At the same time, I don’t think anyone publicly denies that Russia occupies parts of Ukraine. Since 2014, Ukraine has had specific laws addressing the temporarily occupied territories. The bigger question is how effectively this legislation protects the rights and lawful interests of Ukrainian citizens who live—or used to live—there.
— There have been reports about proposals for Russia to “lease” the Donbas while Ukraine formally retains sovereignty. From a legal standpoint, is it possible to transfer certain sovereign powers—such as administrative or judicial authority—without relinquishing the territory itself?
— From the perspective of Ukraine’s Constitution and international law, Crimea, Donetsk, Zaporizhzhia, Luhansk, and Kherson, along with the special-status city Sevastopol, are all integral parts of Ukraine within its existing borders—territory that Russia unlawfully occupied after 2014.
On the other hand, according to the Russian Constitution, the so-called “Republic of Crimea,” the “federal city of Sevastopol,” the “Donetsk People’s Republic,” the “Luhansk People’s Republic,” “Zaporizhzhia Oblast,” and “Kherson Oblast” are treated as new “subjects of the Russian Federation,” which, in Russia’s version, “joined” the country in 2014 and 2022.
So any idea of Russia “leasing” Donbas or other Ukrainian territories contradicts the very logic of the Russian narrative. From Moscow’s perspective, these areas are already under Russian sovereignty, so there’s no reason for them to even consider formalising a lease.
I would also point out that the current territorial situation is even more complicated for several reasons.
First, aside from Crimea and Sevastopol, the remaining so-called “subjects of the federation” (including Luhansk Oblast) are not fully under Russia’s de facto control. From Moscow’s perspective, parts of these areas are still “occupied” by Ukraine. Russia controls over 70 per cent of Kherson, Zaporizhzhia, and Donetsk oblasts, but it doesn’t have complete control—even in Luhansk, according to Ukraine’s administrative boundaries.
Second, the supposed “borders” of these four new Russian “subjects of the federation” were never clearly defined, neither at the time of the 30 September 2022 annexation nor afterwards. That means Russia could potentially redraw or adjust these borders retroactively, possibly incorporating other occupied or unoccupied Ukrainian territories.
Third, Russia has occupied—but not formally annexed—parts of Dnipropetrovsk, Mykolaiv, Sumy, and Kharkiv oblasts. Meanwhile, Ukraine still controls a small area inside Russia’s Kursk Oblast. What Russia plans to do with these territories remains unclear.
— If the United States and some European countries were to formally recognise Russia’s claim to Crimea, what would the consequences be? Would that amount to the end of any realistic prospect of Ukraine restoring control over these territories?
— The international community has largely rallied behind Ukraine’s territorial integrity. For instance, in October 2022, 143 UN member states voted in favour of the General Assembly resolution “Territorial integrity of Ukraine: defending the principles of the Charter of the United Nations.” By comparison, in April 2014, 100 states supported a similar resolution, “Territorial integrity of Ukraine,” which addressed Crimea and Sevastopol.
That said, for Russia to gain an indisputable legal claim to Crimea, Ukraine itself would have to recognise the territory as Russian through the procedure we discussed earlier—an international treaty with Russia plus a nationwide referendum. Until that happens, no matter how many countries formally recognise the annexation, Ukraine’s rights to Crimea remain intact, and the illegal occupation does not become legal.
In general, whether a state recognises a particular legal fact is a sovereign decision. At the same time, international law doesn’t set a fixed threshold for how many states must recognise a new independent state or legitimise an annexation by a third party. Clearly, if countries officially accept the seizure of territory through conquest, such actions can seriously undermine the international legal order. Take, for example, the recognition of Austria’s Anschluss by Western states in 1938—Austria, later described as the first victim of Nazi Germany—and how that ultimately played out (Mexico was the only country to officially protest the Anschluss).
Recognising annexation corrodes international relations. It can backfire on the states that take that step, threatening their own territorial integrity and encouraging the aggressor to push further—particularly as the international legal order weakens and a new one has yet to take shape.
From a legal standpoint, then, a hypothetical US decision to recognise Russia’s annexation of Ukrainian territory would change nothing for Ukraine. Politically, however, it could be another blow to the post-1945 international legal framework. So far, in practice, very few UN member states have recognised the annexation of Crimea—most notably, China has not done so.
— Ukrainian officials sometimes talk about reclaiming Crimea and other occupied territories through diplomacy and legal channels rather than military action. But is that really realistic while Russia in its current form still exists? And are there any comparable cases from the past?
— Let’s be clear from the start: legally, these territories are still Ukrainian. So when we talk about “return,” we really mean restoring de facto control, not re-establishing or proving legal ownership.
Even if, hypothetically, a diplomatic solution were ever to succeed, there would still be the practical challenge of restoring administrative and military control over these areas. If we imagine Russia agreeing to withdraw its troops from mainland Ukraine in an organised way, Ukraine would then need to redeploy its Armed Forces there. And there would inevitably be questions about the Russian naval base in Sevastopol—under the current Constitution, as amended in 2019, foreign military bases are prohibited on Ukrainian soil.
Of course, forecasting is always a tricky business. But in my view, even in the most optimistic diplomatic scenario, we shouldn’t expect a post-Putin Russia to fully and unconditionally withdraw from all Ukrainian territory.
For instance, Russia could at a minimum demand that Ukraine officially recognise Crimea as part of the Russian Federation, enshrine Ukraine’s neutral status in its Constitution (“yes” to the EU, “no” to NATO), and grant a “special status” to Donbas—in exchange for withdrawing troops from mainland Ukraine and removing references to these regions from its own Constitution.
Even in such a scenario, it’s important to remember that Russia would likely try to turn the de-occupied territories into a sort of its very own Trojan horse. The areas returning under Ukraine’s control would face severe humanitarian crises and host a sprawling Russian intelligence network, creating ongoing security and governance challenges.
