"My purpose here today is to assert in my judgment, (ISIS) is responsible for genocide against groups in areas under its control including Yazidis, Christians and Shiite Muslims," he said, during a news conference at the State Department.
Kerry said that in 2014, ISIS trapped Yazidis, killed them, enslaved thousands of Yazidi women and girls, "selling them at auction, raping them at will and destroying the communities in which they had lived for countless generations," executed Christians "solely for their faith" and also "forced Christian women and girls into slavery."
"Without our intervention, it is clear that those people would have been slaughtered," he said.
This is the first time that the United States has declared a genocide since Darfur in 2004.
The House of Representatives on Monday unanimously passed a resolution labeling the ISIS atrocities against Christian groups in Syria and Iraq "genocide," a term the State Department had been reluctant to use about the attacks and mass murders by the terror group.
The genocide finding does not legally obligate the U.S. to take any particular action, but it could put pressure on the Obama administration to take more aggressive military action against ISIS. It could also give weight to calls by other lawmakers and humanitarian groups pushing the Obama administration to welcome more refugees into the United States.The move, aimed at ramping up pressure on the Obama administration, appears to have worked.
The measure was non-binding, but both Republicans and Democrats in the House joined together 393-0 to back a "sense of Congress" saying the crimes committed against Christians, Yazidis and other ethnic and religious minorities in the region amount to war crimes and, in some cases, genocide.
Republican Rep. Jeff Fortenberry, whose Nebraska district is home to the largest group of resettled Yazidis in the U.S., authored the resolution with California Democratic Rep. Anna Eshoo.
During debate on Monday, Fortenberry noted it was a rare instance of an issue that has "risen above the petty and difficult differences we often work out on the floor of the House of Representatives."
Under a deadline set by Congress, the State Department had until Thursday to formally to decide whether it would issue a comprehensive genocide designation.
Kerry, though, had previously alluded to the possibility that the actions of ISIS, also know as ISIL, were genocide.
"ISIL's campaign of terror against the innocent, including the Yazidi and Christian minorities, and its grotesque targeted acts of violence, show all the warning signs of genocide," Kerry said in August 2014. "For anyone who needed a wakeup call, this is it."
Fortenberry praised the State Department for its decision Thursday.
"I commend Secretary Kerry and the State Department for making this important designation. The genocide against Christians, Yazidis and others is not only a grave injustice to theses ancient faith communities -- it is an assault on human dignity and an attack on civilization itself," he said. "The United States has now spoken with clarity and moral authority."