Women clean the temple of Lalish, the most holy site in the Yazidi religion, on Nov. 6 in Iraq. (John Moore/Getty Images)

The Islamic State militant group has been and is continuing to perpetrate a genocide against the Yazidi minority in northern Iraq, a U.S. Holocaust Memorial Museum report says, citing a "preponderance of the evidence" found during a recent trip to the region.

The report, released Wednesday, also details crimes against humanity by the Sunni extremist group involving other ethnic and religious minorities. The report is likely to renew the debate about the fate of the Yazidi people and the use of the term "genocide."

The release of the report coincides with a new Kurdish offensive, backed by a U.S.-led coalition, against the Islamic State in Sinjar, a town that once had a large Yazidi population. The city fell to the Islamic State in August 2014, causing thousands of Yazidis to flee to Mount Sinjar, which was soon besieged by the militants.

The Holocaust Museum's report notes that 40,000 to 50,000 people were trapped on the mountain and that hundreds may have died from starvation and dehydration. In response to the crisis, the United States air-dropped supplies to the stranded. The Yazidis were eventually evacuated.

Last year, as the crisis on Mount Sinjar unfolded, President Obama said the world needed to prevent a genocide against the Yazidi people, but he stopped short of declaring that one was actually unfolding. The United Nations' humans rights agency also released a report earlier this year suggesting that the Islamic State "may have" committed genocide.

The term "genocide" carries significant weight in the international community. It was coined by Polish Jewish lawyer Raphael Lemkin in the 1940s as a response to the Holocaust. The United Nations defines it as "acts committed with intent to destroy, in whole or in part, a national, ethnical, racial or religious group," including killing and forcibly transferring children from the group. The 1948 U.N. convention on genocide requires signatories to work to prevent genocide and punish perpetrators when it does occur.

Over the past half-century, a number of events have been deemed genocides, including the mass killings in Cambodia, the former Yugoslavia and Rwanda. The last time the Holocaust Museum deemed an event a genocide was a decade ago, during the Darfur crisis in Sudan. The U.S. government also labeled that situation a genocide, after months of investigation and disagreement within the State Department.

However, the use of the term is often contested. In 2013, Alex de Waal of the World Peace Foundation at the Fletcher School of Law and Diplomacy at Tufts University urged caution in the use of the word, worrying that countries and institutions are sometimes guilty of "playing the genocide card" and misdiagnosing problems.

The Holocaust Museum's report relies on the research of Naomi Kikoler, deputy director of the museum's Simon-Skjodt Center for the Prevention of Genocide, who recently traveled to the region to investigate the effects on civilians of a summer 2014 Islamic State offensive in the Iraqi province of Nineveh.

Kikoler found that almost 800,000 members of minority groups have since fled from the province, leaving almost no one from these communities behind. A large number were killed during the violence, and it is possible that thousands remain hostages of the Islamic State, including women and children.

The report found that crimes against humanity, ethnic cleansing and war crimes had been committed against Christian, Turkmen, Shabak, Sabaean-Mandaean and Kaka’i people by the Islamic State, but it stated that only the Yazidis had a genocide perpetrated against them. The report did state, however, that Shitte Shabak and Shiite Turkmen were at risk of genocide.

The about 500,000-strong community of Yazidis in northern Iraq — followers of a unique 4,000-year-old faith that draws upon Zoroastrianism, Islam and other religions — have long faced persecution in the region, where they are sometimes referred to as "devil-worshipers." Yazidis say that throughout history there were purportedly 72 other attempts to wipe out their group.

Kikoler found that during the Islamic State's advance on Nineveh, between June and August 2014, the Yazidis were attacked in ways that appeared to constitute a genocide. Possibly more than a thousand were killed by Islamic State fighters in this period, including in mass massacres. The kidnapping and sexual slavery of Yazidi women and children by the Islamic State was not only an attempt to terrorize the community, but also a bid to prevent new Yazidi births and to deprive children of the opportunity to grow up in their own culture, the report says.

Many of these women and children are still held by the Islamic State.

Crucially, Kikoler argues that Islamic State publications show that this attempt to wipe out the Yazidis was planned by the Islamic State and crucially differed from how it treated other religions. "IS specifically notes that its treatment of the Yazidis differs from its treatment of ahl al kitab, the 'people of the book,' Christians and Jews, who had the option of paying the jizya (tax) to avoid conversion or death," Kikoler writes in the report. "By refusing Yezidis any option to avoid death or forced conversion, IS demonstrates that its actions were calculated with the intent of destroying the community and thereby different from its attacks against other minorities, which were part of a campaign of ethnic cleansing."

In the past, the Holocaust Museum has been cautious when using the word "genocide," sometimes suggesting that there was a risk of genocide rather than stating that one had actually occurred. The latest report notes that although it believes that what happened to the Yazidis was a genocide, a court of law needs to rule on it definitively.

If it is agreed that the actions against the Yazidis constitute a genocide, it is unclear how the international community — or the U.S. government, which is a signatory of the 1948 genocide convention — would react. Some reports suggest that the U.S. government is planning to begin using the term in the coming weeks, hoping that it will increase pressure on others to act against the Islamic State. Some Yazidi activists hope that the use of the word can strengthen eventual investigations and trials at the International Criminal Court.

"For Yazidis, it is very important to secure recognition that a genocide was committed against us,” activist Pari Ibrahim told the Middle East Eye this week. “The word genocide is important, and starting an ICC case will eventually bring recognition, reparations and ensure the protection of civilians in the future.”

More on WorldViews

The Islamic State isn’t the only group looting Syrian archaeological sites

The dispute between al-Qaeda and the Islamic State has devolved to name-calling