KIEV — A rising number of civilian casualties in Ukraine has prompted accusations that Moscow has committed war crimes in its relentless bombardment of non-military targets in cities, as well as its alleged use of weapons that heighten the risk of death and injury for non-combatants.

In pursuit of evidence, Ukraine's government has opened a new front in the conflict, dispatching visual teams to bombed sites to make a case against Russia at the International Criminal Court in The Hague.

Last month, the prosecutor of the ICC announced the opening of an investigation into possible war crimes unfolding in Ukraine — a move welcomed by the EU heads of state and government during their summit meeting in Versailles on Friday.

War crimes, under international law, include the targeting of civilians, as well as assaults that cause disproportionate civilian casualties given the military objective. This includes attacks on hospitals, clinics, schools, historic monuments and other key civilian sites, as well as attacking or bombarding towns, villages or dwellings that are undefended and which are not military objectives.

Still, many horrific acts of violence that result in the deaths of non-combatants would not meet the criteria. And in most cases, proving that civilian killings constitute a war crime is very difficult.

“A standard for conviction in an international criminal court is extremely high,” Marti Flacks, director of the Human Rights Initiative at the Center for Strategic and International Studies in Washington told Euronews.

“The expectation for prosecuting someone for war crimes and crimes against humanity is to be able to demonstrate individual responsibility and be able to demonstrate that they are directing or responsible for a policy of committing these crimes.

“And that can be very difficult, especially when you don't have the cooperation of the state from which that kind that person originates, which we would obviously not have in the case of Russia.”

In order to indict someone, the ICC prosecutor must prove that the alleged crimes are atrocity crimes: genocide, crimes against humanity or war crimes. The prosecutor determines gravity by looking at the scale, nature, manner and impact of the alleged crimes.

The ICC tries individuals. It does not try states. For instance, in the current conflict, Russia would not be a defendant, but Vladimir Putin could be a defendant.

Once enough evidence is found to establish reasonable grounds that atrocity crimes were committed, the prosecutor may request an ICC chamber issues an arrest warrant for Putin — but making a case under current circumstances might be complicated.

“Obviously, any criminal prosecution requires a number of steps, including collection of physical evidence, interviewing and collection of witness testimony, collection of contextual information and documentation that explain the circumstances where crimes were committed. And trying to do this in the context of an ongoing active war makes it difficult to do so," Flacks said.

If the ICC issued an arrest warrant against Putin, his ability to travel would be severely restricted. “If Putin or someone in his leadership were sought by the ICC, all 123 members of the Rome Statute of the International Criminal Court would be obligated to turn them over to the ICC,” Flacks explained.

Practically speaking, in order for Putin and other senior leadership to face any kind of charge, there would have to be regime change in Russia — the idea that Putin would be arrested by his own government is simply not conceivable.

If there were to be charges, and if Putin remains head of state, it becomes very complicated, as was the case with other heads of state who have been indicted and then not brought to bear before the ICC for years because they take steps to avoid physical presence before the court. This is important, as the ICC does not try individuals in absentia.

Whether or not Putin and other top military and political officials will ever be indicted, it will likely take years to come to a verdict.

“ICC prosecutions can take a very long time. The case that the ICC began investigating for the Russian invasion of Ukraine in 2014 is still proceeding”, Flacks highlighted. “And we know that prosecutions that began at the early days of the ICC back in the early 2000s are in some cases still going on today.”

Ukraine is also pursuing another avenue to hold Russia accountable for the crime of aggression through the International Court of Justice, which has scheduled public hearings. This UN court deals with disputes between countries, and so would not result in any criminal charges against Putin the individual. — Euronews