The chief prosecutor of the International Criminal Court (ICC) and several European countries have opened investigations into suspected war crimes being committed in Ukraine.
Attacks on civilians and critical infrastructure, including the bombing of a maternity and children's hospital on Wednesday, have prompted international outrage.
While many countries and international bodies have accused Russia of violating international humanitarian laws, Russia has firmly denied targeting civilians in its invasion of Ukraine.
So what happens if a case can be made against Russia, who could potentially be charged, and which courts have the authority to try such a case?
What is a war crime?
Simply put, a war crime is a violation of internationally agreed laws or customs that govern what is acceptable and what is unacceptable during war.
This can include: intentionally targeting civilians, using certain types of indiscriminate weapons, murdering or torturing prisoners of war, systematic slavery and rape and widespread destruction that is not militarily necessary.
War crimes can include small and large scale campaigns, as well as individual attacks on both civilians and combatants.
Along with war crimes, Russia has also been accused of committing crimes against humanity in Ukraine — a charge it too rejects.
While the two categories are closely linked and often overlap, crimes against humanity is a term applied to widespread crimes against a civilian population committed either in or out of war.
"A crime against humanity needs to be part of what we call a systematic attack on a civilian population ... a more systematic campaign of violence, which clearly is part of what is going on in Ukraine," explained Ben Saul, a Professor of International Law at The University of Sydney.
Professor Saul said "the kind of widespread indiscriminate bombardment of cities" that is happening in Ukraine could constitute both a war crime and a crime against humanity.
Who decides what constitutes a war crime?
While various codes of war have been followed throughout history, the development of a specified international definition of what constitutes a war crime started with the Hague Conventions.
They were adopted early last century and prohibit the use of certain methods of warfare.
Some violations of this are considered war crimes, as are some violations of the Geneva Conventions that focus on the protection of civilians.
War crimes are also listed in both international humanitarian law and international criminal law treaties, as well as in international customary law.
While the 1949 Geneva Conventions were ratified by all Member States of the United Nations, additional protocols and other international humanitarian law treaties have not been signed by all countries.
In 2002, the ICC was established to prosecute international war crimes, crimes against humanity, genocide and the crime of aggression where national courts are unable or fail to do so.
The ICC has jurisdiction only within countries that grant it jurisdiction, and so far only 123 nations have signed on.
The US, Russia and China are not among them.
Ukraine, a non-ratifying signatory, has accepted the ICC's jurisdiction for a period starting in 2013.
The ICC opened its investigation of current events in Ukraine on March 2.
"The scope of the situation encompasses any past and present allegations of war crimes, crimes against humanity or genocide committed on any part of the territory of Ukraine by any person from November 21, 2013 onwards," the ICC said.
Who could try Russia for alleged crimes in Ukraine?
Every country has the power to prosecute war crimes in their national legal systems.
This week, Germany and Spain announced they had opened investigations into Russian war crimes in Ukraine.
Germany has in the past repeatedly prosecuted atrocities committed abroad, including the war in Syria.
Alternatively, a special international tribunal could be set up by a number of participating countries.
While the ICC can investigate Russian crimes in Ukraine, they have no legal obligation to cooperate with the court or hand over suspects for trial or prosecution.
Those who could be prosecuted include:
- Anyone who physically commits a war crime
- Anyone aiding or abetting war crimes
- Commanders ordering crimes or failing to stop known crimes of their subordinates
- Civilian leadership found to be criminally responsible such as state leaders, ministers or cabinet members
This means even Russian President Vladimir Putin could be tried for war crimes.
How common are war crimes and how often are they prosecuted?
While war crimes are common and can be committed by all sides to some degree, they are very difficult to prove, especially when it comes to senior command and state leaders.
"It has to be shown that they're aware of what their troops are doing on the ground, and they have power over them and they're not doing anything to stop it," Professor Saul said.
Putting a head of state behind bars for such crimes can be even more difficult.
"It is relatively rare, because in order to do so it presumes you've completely vanquished the country and managed to get your hands on their leader."
This did happen in Iraq, where Saddam Hussein was prosecuted and executed by an Iraqi special international tribunal.
However, in Syria, Bashar al-Assad and senior defence leaders have been convicted of war crimes but remain in power.
"If Ukraine manages to detain Russian soldiers on the battlefield as prisons of war then they can be prosecuted if there's evidence against any of them," Professor Saul added.
He also stressed the need to look internally when it comes to international crimes.
He said while Australia is doing better with its current investigations into war crimes committed in Afghanistan, the United Kingdom, United States and Israel "have been terrible in prosecuting their own soldiers".
"That's why a much more concerted effort needs to be put into justice and accountability for war crimes, not just for our geo-political rivals like Russia but for ourselves."
