Biden calls Russia's invasion of Ukraine a 'genocide.' Is it a war crime?

President Joe Biden called Russia's attack on Ukraine a "genocide" on Tuesday while talking with reporters before heading back to the White House from Iowa.

The statement came after Russian President Vladimir Putin said peace talks had reached a "dead end" and Russian troops would not leave Ukraine until the Kremlin's goals are accomplished.

“It’s become clearer and clearer that Putin is trying to wipe out the idea of being Ukrainian,” Biden said.

More than 10,000 civilians have been killed in the city of Mariupol since the beginning of the invasion in February, Mariupol Mayor Vadym Boychenko said Monday.

Live Ukraine updates: New US sanctions will force Putin to focus on Russian economy over war, officials say

'A full-fledged pariah state': Senate votes 100-0 to end Russia trade status, enact oil ban

Ukrainian President Volodymyr Zelenskyy has called the acts of Russia in Ukraine a genocide, and Biden said it would be up to international lawyers to see if the term fits.

“More evidence is coming out literally of the horrible things that the Russians have done in Ukraine,” Biden said.

How do you define genocide?

According to the United Nations, genocide is defined as intentionally destroying, in whole or in part, a national, ethnical, racial or religious group, by one of these acts:

• Killing members of the group.

• Causing serious bodily or mental harm to members of the group.

• Deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part.

• Imposing measures intended to prevent births within the group.

• Forcibly transferring children of the group to another group.

"The crime of genocide may take place in the context of an armed conflict, international or non-international, but also in the context of a peaceful situation," according to the United Nations' website.

The term was first recognized under international law in 1946 by the U.N. General Assembly. The 1948 Convention on the Prevention and Punishment of the Crime of Genocide codified the act as an independent crime.

Is genocide a war crime?

Genocide can be considered a war crime if it is committed during a war, said Harold Hongju Koh, an international law professor at Yale Law School.

It also can be committed during peacetime, which makes it an international crime such as the Rwandan genocide in 1994, in which more than 800,000 people were killed after the majority ethnic Hutus targeted the smaller Tutsi population and others.

How do you prove genocide?

Koh told USA TODAY that to prove genocide, there has to be a high level of intent.

"The tricky part of it which is relevant to the president's statement yesterday is if I kill one person, that's homicide," he said. "If I kill that person with the intent to destroy every person of that person's ethnic group, then it could be a part of genocide, but you don't know."

Koh, who was a legal adviser to the State Department under President Barack Obama, said there is a process the State Department follows to determine whether genocide has been committed.

What's everyone talking about? Sign up for our trending newsletter to get the latest news of the day

"Four of its bureaus meet to go over all the evidence and decide whether they can call it war crimes, crimes against humanity or genocide," he said.

It can take several months to make a declaration of genocide before it becomes official.

"Proving an intent to destroy an entire group is difficult, because it's not that often someone says 'I have intent to destroy the entire group,'" Koh said. "You don't have a smoking gun that often."

How many genocides have there been?

Since the 1900s there have been multiple documented genocides, including the Armenian genocide in 1915, the Holocaust in 1941, and the Bosnian genocide beginning in 1992, when an estimated 100,000 people were killed.

In 2003, a genocide occurred in Darfur, Sudan, where an estimated 400,000 people died in the conflict, according to The Genocide Education Project.

Contributing: Rebecca Morin

Follow reporter Asha Gilbert @Coastalasha. Email: agilbert@usatoday.com.

This article originally appeared on USA TODAY: Genocide meaning: Biden calls Russia attack against Ukraine 'genocide'