THE TRUMP administration, Congress and most other Western governments have gingerly responded to the assault by Myanmar’s army on the country’s Rohingya minority, though it stands out as one of the most vicious and destructive campaigns of ethnic cleansing in recent history. Just five military commanders and two army units have been sanctioned by the Treasury Department, while congressional sanctions legislation was blocked by Senate Majority Leader Mitch McConnell (R-Ky.). The State Department has yet to release a promised report on what it has termed an act of ethnic cleansing.

So it was bracing as well as constructive that a three-member panel appointed by the United Nations to investigate Myanmar’s wars against the Rohingya and other minorities did not prevaricate in a report issued this week. Instead, the Independent International Fact-Finding Mission on Myanmar bluntly concluded that “The gross human rights violations committed . . . are shocking for their horrifying nature and ubiquity” and “undoubtably amount to the gravest crimes under international law.”

The panel called for senior army officials to be investigated and prosecuted on charges of genocide, and named six top suspects, including Commander in Chief Min Aung Hlaing — who, so far, has escaped sanctions and other meaningful international censure. Only two of the six are on the U.S. sanctions list. Their report charged that, despite official claims that the army was responding to a wave of attacks by Rohingya militants, the campaign was conceived and planned in advance by Mr. Hlaing and his subordinates, who deployed troops and other assets to Rakhine state well before the insurgent attacks of Aug. 25, 2017.

The army operations, said the report, “were strikingly similar.” Troops would arrive at a village early in the morning, firing indiscriminately at civilians. Men and boys would be rounded up and taken away, while women and girls were subjected to mass gang rapes. Many were herded into houses, which were then set on fire. At least 392 villages were partially or totally destroyed, the investigators found; by mid-August 2018, nearly 725,000 Rohingya had been driven across the border into Bangladesh, where most still live in overcrowded camps. While the death toll is unknown, the panel said an estimate of up to 10,000 killed was “conservative.”

Mr. McConnell and some in the administration have resisted a tougher response to these horrific crimes because of their sympathy for Aung San Suu Kyi, who led Myanmar’s partial return to democracy. The theory is that the Nobel Peace laureate, who now controls the civilian government, has no authority over the military. But the U.N. verdict on her government is unsparing: Aung San Suu Kyi, it concludes, “has not used her de facto position as Head of Government, nor her moral authority, to stem or prevent the unfolding events.” Rather, it says, “civilian authorities have spread false narratives; denied the [army’s] wrongdoing; blocked independent investigations . . . and overseen destruction of evidence.”

The investigators’ call for the U.N. Security Council to refer the case of Myanmar, also known as Burma, to the International Criminal Court is unlikely to be taken up; Mr. Hlaing was recently seen in Russia on an arms-buying mission. But the Trump administration should apply its own sanctions to the military commander in chief and others named in the report, and cut off all cooperation with the military. Secretary of State Mike Pompeo should ensure that the State Department’s report is as honest as that of the U.N. panel. Genocide must be called by its name.

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