Ukraine has accused Russia of committing "war crime" after Vladimir Putin ordered an invasion of the country, destroying buildings and killing innocent civilians.
The country's president Volodymyr Zelensky spoke after a missile hit the centre of Kharkiv.
He also condemned a rocket attack on the city of Kharkiv on Monday which killed at least nine people.
Mr Zelenskiy said: "This is terror against the city. There was no military target on the square … No one will forgive, no one will forget."
He added: "This attack on Kharkiv is a war crime. This is state terrorism of the Russian Federation. After that, Russia is a terrorist state … We demand full responsibility for terrorists in international courts."
Here is everything you need to know about war crimes - from the history of the International Criminal Court to its work.
What is the International Criminal Court?
The ICC was established in 2002 under the Rome Statute, which was agreed at a conference in the Italian capital in July 1998. It was set up to prosecute individuals and their commanders accused of crimes in cases where nations are unable or unwilling to hold their own trials.
What can it investigate and prosecute?
Based in The Hague in the Netherlands, its remit extends to war crimes,
crimes against humanity, genocide and the crime of aggression. Its website currently lists 16 investigations and 46 defendants.
What is a war crime?
The Geneva Conventions set out the rules of war - what is acceptable when states fight each other. Conduct not sanctioned by the Conventions could constitute war crimes. According to the ICC they can involve “serious violations of the laws and customs applicable in international armed conflict”.
What does that mean?
The International Committee of the Red Cross says “violations are serious, and are war crimes, if they endanger protected persons (e.g. civilians, prisoners of war, the wounded and sick) or objects (e.g. civilian objects or infrastructure) or if they breach important values”. Bombing obviously civilian targets such as blocks of flats, schools and hospitals are examples.
Has Russia committed war crimes in Ukraine?
The ICC’s chief prosecutor Karim Khan today said there was "reasonable basis" to believe war crimes or crimes against humanity had been committed by Russian forces during the invasion. Instances he could examine include a tank driving over a car - apparently deliberately - on Friday in Kyiv. Another example could include the bombing of a residental apartment block in Kharkiv in which three children were killed.
Were crimes committed in the former Yugoslavia heard by the ICC?
Some of the most infamous war crime prosecutions of recent years stemmed from the civil war unleashed by the breakup in the Balkans. But cases were heard by the International Criminal Tribunal for the former Yugoslavia because the ICC did not exist.
The hearings, including into Serb leader Slobodan Milosevic, demonstrated the need for a permanent court. Radovan Karadžić, a Bosnian-Serb former politician who served as the President of Republika Srpska during the Bosnian War, was convicted of genocide, crimes against humanity and war crimes by the Tribunal.
He was jailed for 40 years. Last May it was announced he was being transferred to a British prison to serve the rest of his sentence.
