It's a move aimed at ramping up pressure on the Obama administration. 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, Yezidis and other ethnic and religious minorities in the region amount to war crimes and in some cases, genocide.
Republicans Rep. Jeff Fortenberry, whose Nebraska district is home to the largest group of resettled Yezidis 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 has until March 17 to formally to decide whether it will issue a comprehensive genocide designation, but it is expected to miss the deadline.
"This is threat against civilization itself when a group of people, ISIS -- 8th century barbarians with 21st century weaponry -- can systematically try to exterminate another group of people simply because of their faith tradition violating the scared space of individuality, conscience and religious liberty, you undermine the entire system of international order," Fortenberry said.
California Democratic Rep. Brad Sherman concurred.
"It is clear that as least some of the war crimes are part of a planned genocide against the religious minorities in areas that ISIS occupies," he said.
State Department spokesman John Kirby said Monday that Secretary of State John Kerry would "reach a determination soon."
"Regardless of whether their conduct satisfies certain legal definitions, including genocide and crimes against humanity, the United States has been clear that our interest in accountability for the perpetrators remains undiminished," Kirby said.
After the vote the House Majority Leader Kevin McCarthy called out the administration for failing to officially label the crimes.
"We know what they are doing and if we don't say it we should be ashamed -- ISIL is committing genocide," he said.
The House also passed another nonbinding resolution on Monday that directs the United Nations to create a war crimes tribunal to investigate the government of Syria and allies in the region for potential international violations.