The massacre and expulsion of Rohingya by Myanmar’s military last year is now being described as a genocide by the United Nations.

In a report released Monday, the UN describes the events as a “foreseeable and planned catastrophe” and that genocidal intent can be gleaned from “the level of organization indicating a plan for destruction; and the extreme scale and brutality of the violence.”

Six generals are identified as the chief culprits of the genocide, including the army’s commander in chief, senior general Min Aung Hlaing, the New York Times reports. The United Nations recommends all six to be investigated by the International Criminal Court (ICC) for actions that “undoubtedly amount to the gravest crimes under international law.”

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Prior to the ethnic cleansing and mass expulsion of Rohingya from Myanmar’s Rakhine state in August 2017, the country’s military and public officials seemed to be making preparations for a bloody crusade, according to the United Nations.

Toward the end of 2016, sharp tools were removed from Rohingya homes, fences were destroyed, aid was cut off from communities, and army convoys were stationed throughout Rakhine state. This was on top of a decades-long efforts to oppress and deny Rohingya citizenship. Something seemed to be underway.

Then, when small bands of Rohingya insurgents armed with swords attacked military compounds in 2017, an all-out military campaign began.

The resulting effort was so brutal and totalizing that United Nations’ officials swiftly described it as an ethnic cleansing. In a matter of months, more than 723,000 Rohingya were forced to flee their homes, 25,000 people were killed, thousands more were raped, maimed, and injured, and whole communities were razed.

“The crimes in Rakhine state, and the manner in which they were perpetrated, are similar in nature, gravity and scope to those that have allowed genocidal intent to be established in other contexts,” the UN’s report latest said.

That finding has been supported by the human rights group Fortify Rights, which independently conducted extensive fact-finding missions into the situation, interviewing hundreds of affected people, and reviewing public and other records.

“These findings are devastating and highly significant,” said Matthew Smith, chief executive officer at Fortify Rights. “This will necessarily shift the thinking of UN member states— business as usual is no longer an option. The next logical step is for member states to ensure those responsible are held accountable.”

Read More: What the Rohingya Refugee Crisis Looks Like, 1 Year Later

The bar of evidence for a genocide is immense, and the term has only been applied to a handful of events in history, but Fortify Rights argues that the evidence is strong.

“This report, which adds to a mountain of evidence of crimes under international law committed by the military, shows the urgent need for independent criminal investigation and is clear that the Myanmar authorities are incapable of bringing to justice those responsible,” said Tirana Hassan, director of crisis response at Amnesty International, referring to the UN’s report.

“The international community has the responsibility to act to ensure justice and accountability. Failing to do so sends a dangerous message that Myanmar’s military will not only enjoy impunity but is free to commit such atrocities again,” she added.

Rohingya refugees also have enough cell phone footage to make a case for genocide in international courts, according to the Times.

Various human rights organizations and politicians across Southeast Asia are calling on the ICC to investigate military officials for human rights violations and genocide.

Read More: Timeline: How the Rohingya Crisis Unfolded in Myanmar

In the meantime, groups are also calling for sanctions to target these figures. Next, the ICC can investigate and bring additional charges to responsible actors.

“The UN Security Council must refer the situation in Myanmar to the International Criminal Court as a matter of urgency,” Hassan said. “Until it does, it’s vital that countries establish a mechanism through the UN to collect and preserve evidence for use in future criminal proceedings.”