Andriy Kostin is Prosecutor General of Ukraine. Speaking to IBA Executive Director Mark Ellis, he discusses the impact of Russia’s invasion of Ukraine on the world legal order and considers the challenge of prosecuting the crime of aggression and Russian war crimes in general.

Mark Ellis (ME): Russia's invasion of Ukraine has violated some of the fundamental international principles that were established at the end of the Second World War. If Russia were able to succeed in this war, what would that mean to the modern legal order?

Andriy Kostin (AK): In this case, the world’s legal order would be completely destroyed. That's why we are engaging such a wide support in order to win this war for freedom. War for democratic values. War for human rights. War for people's dignity.

You mentioned the end of the Second World War. At that time, we had a set of international tribunals which investigated and prosecuted horrendous war crimes committed in different parts of the world, including Europe. Why has Europe had long lasting peace and order after the Second World War? Because all perpetrators were held accountable by the Nuremberg Trials and the Tokyo War Crimes trial. The United Nations (UN) was then established and the UN Charter which, as an element of fundamental value, offered peace and order.

Accountability for war crimes – including crimes against peace at that time, which we now call crimes of aggression – gives Europe and the world decades of peace and stability. Therefore, now we have no chance to lose this war. Because if you think that the front line is on Ukrainian territory, you are just not admitting that the front line is everywhere. If we lose, that frontline will be everywhere because aggressors will enjoy impunity for every crime they have committed, starting with the crime of aggression.

ME: You've undertaken this initiative to ensure that there are domestic prosecutions for war crimes, but you also seem to be broadening this into other areas. What's the mosaic for you in Ukraine on prosecuting the types of atrocities being committed?

AK: We know that it's our primary responsibility to investigate, document and prosecute all war crimes committed during the course of this aggression. When I say all, we are talking about all incidents of war crimes. We are talking about all types of war crimes, since there is no war crime you can imagine that has not been committed by Russia in Ukraine against Ukrainians.

We need to stop it, including the crime of genocide. It's not only about the forcible displacement of Ukrainian children and putting them under illegal adoption in Russian families. It's also about cases where war crimes were so concentrated in specific territories, it could lead to the level of genocide.

And don't forget about the intent, which was publicly mentioned by President Putin and many Russians, to erase Ukrainians from their nationality, from their motherland, from their culture and from their history altogether. We believe it was committed and we need to establish a full evidentiary base. We have standards of investigation and prosecution of international crimes. These standards are applied by all investigative authorities and prosecutors. We completely changed our approach because we understood that these horrendous crimes were being underreported. We changed to a victim-centred approach and now we have many more reports from people.

Then we proceed with specialised types of crimes which were never prosecuted before as war crimes. Crimes against the environment, which were never investigated and prosecuted before as war crimes. Cyberattacks as war crimes have never been prosecuted before. But we need to be prepared because if we prosecute, if we find them accountable for these, it will have a deterrent effect. Once again, we know that this war is global and what we are doing is not only for us. It's for everyone. That's why we’re taking these new avenues.

It's also about creating a partnership on a higher level to ensure that crime of aggression will be prosecuted, including against incumbent President Putin and other members of the troika. We can't let them go unpunished.

ME: The International Criminal Court (ICC) does not have jurisdiction over the crime of aggression against Ukraine. That would require an international tribunal. Do you believe that the international community will create a new international tribunal for the crime of aggression? Or do you think it will be in a different model?

AK: I believe that a special tribunal should be created. It should have jurisdiction over Putin and other members of the troika, and it should be of international dimension because the crime of aggression is an international crime. In order to prosecute and to punish those who are advancing this aggressive war, the response should be international, because in that respect, not only Ukrainian victims of this war will receive their feeling of justice, but also it will play a deterrent effect.

Not every potential aggressor in the world is a member of the Rome Statute. We understand that the ICC has limited jurisdiction. We also understand that the UN Security Council unfortunately, in most cases, will not serve as an efficient instrument because of the veto rights which exist in the Security Council. So that's why we need to create an international mechanism to prosecute and to punish those who started this war of aggression.

While legal discussions are ongoing, we are not waiting. In Eurojust [the European Union Agency for Criminal Justice Cooperation] in The Hague, we have launched the International Centre for the Prosecution of the Crime of Aggression, which includes Ukrainian prosecutors among members of the joint team of Estonia, Latvia, Lithuania, Poland, Romania and Slovakia, and is seconded by the US Department of Justice (DoJ). They are already building this case and preparing for the future tribunal.

We understand that discussion is not very easy. But one year ago, there were only a few countries who officially supported the idea of a tribunal. Now we are talking about legal modalities. The only condition Ukrainians will accept is that Putin and other members of the troika are prosecuted and tried by this tribunal. This is important not only for Ukrainians to feel justice, but so we do not forget about Ukrainian servicemen – Ukrainian military servicemen who yesterday were civilians and who are killed in the course of this aggressive war protecting our land. And if Russian leadership is not held accountable for this crime of aggression, it will mean that our Ukrainian servicemen were killed without any punishment.

ME: The ICC has opened its first office outside of The Hague in Ukraine, and yet Ukraine is not a State Party to the Rome Statute. Why hasn't Ukraine signed on to the Rome Statute if, in fact, the ICC is playing such an important role in assisting Ukraine in ensuring that there's accountability for the crimes being committed by Russia?

AK: First of all, there is a full set of national legislation which allows the ICC to conduct their activity. Already you see the results of our historic partnership with Prosecutor [Karim] Khan’s team. First, the arrest warrants, not only against high level Russian officials, but against Putin. It's not only historic in its sense but also in its speed, because the ICC has previously been criticised as a slow working institution. Now, with the team of Prosecutor Khan, whom I personally commend for their commitment to work, and the opening of the field office, I see a sign of sustainable work from the ICC in Ukraine for years because war crimes will be prosecuted and investigated for years and maybe even for decades.

Regarding the Rome Statute, my position was always that Ukraine should ratify the Rome Statute. It's in the hands of the parliament and I believe in the coming future you will see the Rome Statute ratified. From the point of view of the work of Prosecutor Khan and the ICC, they have a full set of instruments to do it.

ME: The US has played a critical role in defending Ukraine, providing military financial support to Ukraine, as well as other European countries. But there are now questions about whether there will continue to be support from the US for Ukraine in the war against Russia. How worried are you about this paradigm shift in the US? What does it mean for the efforts in Ukraine?

AK: For us, our fight for our freedom, territorial integrity and sovereignty is equal to our fight for justice for all victims and survivors of this war. These are two issues which are interlinked because there could be no long-lasting peace without justice. What I feel from our partners and friends from the US is a unique level of support. Our cooperation with the DoJ, the State Department and other institutions in our accountability endeavours is also historic.

Let's think also about the law, which was passed last December by the US Congress, allowing the US to cooperate with the ICC in the case of Ukraine. This is an incredible first step. Let's mention once again the DoJ, who is a partner of our joint investigation team. They are helping our prosecutors, working with them to build the case on the crime of aggression, unique elements of which were never seen and never predicted before from the point of view of the US. So, we are understood. We are heard. We are in an open and transparent discussion.

It's also about sending a signal to Russia that there will be no safe haven, even when years have passed for them to travel safely somewhere. Your question is very important to Ukrainians, to Ukraine and, actually, to all of you. We need to win in both fights. We are sure that our support from the US, the EU and from many other countries will be long-lasting for as long as we need, because it's not only for us, but also for all of you.

This is an abridged version of Andriy Kostin’s interview at the IBA Annual Conference in Paris. The filmed interview can be viewed in full here.