A stunning new report asserts that a U.S. intelligence official formally blew the whistle on President Donald Trump for making a disturbing pledge to a foreign leader.

According to the Washington Post, the whistleblower’s complaint — which has sparked a battle between the intel community and Congress — centers around Trump’s interaction with an unnamed head of state.

From the report, by Greg Miller, Ellen Nakashima, and Shane Harris:

Trump’s interaction with the foreign leader included a “promise” that was regarded as so troubling that it prompted an official in the U.S. intelligence community to file a formal whistleblower complaint with the inspector general for the intelligence community, said the officials, speaking on the condition of anonymity because they were not authorized to discuss the matter publicly.

The Post goes on to note that Intelligence Community Inspector General Michael Atkinson has deemed the whistleblower’s complaint to be a matter of “urgent” concern. That designation typically prompts Congressional oversight. But Joseph Maguire, the acting director of national intelligence, has refused to disclose the particulars of the alleged incident — moving some to question whether he is overstepping his bounds by shielding the president in this way.

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