So what does that designation mean? ABC News breaks it down.
Why does it matter that the Obama administration uses the word “genocide?”
There has been increasing pressure on the Obama administration to declare the actions of ISIS genocide.
Many other organizations have also advocated for the administration to do so.
A senior aide to Kerry said using the word also means the history of the situation will be better documented, while acknowledging and recognizing the suffering of victims.
How could ISIS be punished?
Punishment or prosecution can happen through several channels.
“It will take years to build those cases,” Naomi Kikoler, Deputy Director of the Simon-Skjodt Center for the Prevention of Genocide, told ABC News.
Kikoler, who authored a report on genocide against Iraqi minorities and has traveled to the region, said despite the lengthy timeline, there are steps the U.S. can take now, like documenting atrocities committed by ISIS and gathering and preserving evidence.
Sec. Kerry said today that the U.S. will “strongly support efforts” to do just that.
“We will do all we can to see that the perpetrators are held accountable,” he said.
But a senior aide to Kerry said it does not necessarily mean changing military strategy or changes in the refugee system.
Why could prosecution deter ISIS fighters?
For an organization like ISIS -- whose goal is to commit genocide and wipe out populations that disagree with their thinking -- Kikoler said the threat of prosecution may not be a deterrent.
But that doesn’t mean there isn’t value in designating their acts as genocide.
Kikoler said foreign fighters may be more likely to be deterred if they know their crimes lead to life in jail.
Even more importantly, actors enabling ISIS by providing weapons or funding could be prosecuted for aiding and abetting genocide.
Who’s responsible for preventing genocide?
The United Nations says that while individual countries have the primary responsibility to protect populations from genocide, the international community also has a responsibility to encourage and assist states in doing so.
"If a State is manifestly failing to protect its populations, the international community must be prepared to take collective action to protect populations, in accordance with the Charter of the United Nations,” the U.N. says on its website.
Those airstrikes, along with assistance by the Kurds and American forces, allowed the majority of the 50,000 Yazidis to flee into the mountains and be evacuated.
What happened after the last time the U.S. declared genocide?
In 2009, the Sudanese president became the first sitting president to be indicted by the ICC for his alleged role in ordering mass slaughter and rape in Darfur. However, the ICC has not been successful in its prosecution because Omar al Bashir was never turned over.
Genocide continues in Darfur.
Where did the term “genocide” come from?
The word was created in 1944 when Polish-Jewish lawyer Raphael Lemkin wanted to describe how the Nazis were committing systematic murder of Jews. He combined “geno,” from the Greek word for race or tribe, with “cide,” which comes from the Latin word for killing.
When the International Military Tribunal charged Nazis with crimes against humanity in 1945, the word genocide was included as a descriptive term.
Three years later, the United Nations approved the CPPCG, which established genocide as an international crime.
ABC News' Justin Fishel contributed to this report.