Nadia Murad, a Yazidi who escaped captivity in 2014, told the Senate Homeland Security committee that "the USA must act. We must terminate Daesh (ISIS) and all such terror."
"Daesh will not give up their weapons unless we force them to give up their weapons," she testified, with the assistance of a translator. "The Yazidi people cannot wait."
Murad called on the U.S. and other countries "to establish a safe and protected zone for Iraqi and Syrian religious minorities," which President Barack Obama has repeatedly rejected.
She also expressed her condolences for the attack in Orlando that left 49 dead but said she was not surprised it happened.
"I knew if ISIS were not stopped, they would deliver their crimes everywhere," she told lawmakers.
Speaking about the Middle East's Christians, Yazidis, and other minorities, she warned that "if they are not protected they will be wiped out."
Yazidis are ethnically Kurdish members of an ancient religion who live mostly in Iraq.
Murad detailed how she and thousands of Yazidi women and girls were enslaved and raped by their ISIS captors. She recounted how six of her brothers and her mother were executed by ISIS in a single day.
Murad said she escaped to Mosul where a Muslim family helped her obtain fake Islamic identification that enabled her to escape ISIS territory.
"I was freed, but I do not (have) the feeling of the freedom because those who have committed these crimes have not been held accountable," she said.
A UN report released last week estimated that ISIS holds about 3,500 slaves and that the terror group continues to subject women and children to sexual violence, particularly in the form of sexual slavery. The report said ISIS' actions "may, in some instances, amount to war crimes, crimes against humanity, and possibly genocide."
Secretary of State John Kerry said in March that the U.S. had determined that ISIS' brutality constituted genocide.
With the genocide designations, Murad called on the international community to take ISIS to the international criminal court.
Murad also called on the Islamic community around the world to do more to denounce ISIS.
"What has been happening has been happening under the name of Islam," she said. "The Muslims must be the first ones to resist this ... We have not seen that Daesh have been labeled as an infidel group within Islam by any Muslim country."
When asked by Sen. Tom Carper of Delaware whether the U.S. should accept more refugees from the region, Murad responded, "Every country has the right to protect itself and its borders but the people who are escaping from the religious discrimination and genocide should not face closed doors."