The Washington Post reports that a conversation between President Trump and a world leader disturbed a U.S. intelligence official so much that the person filed a whistleblower complaint — leading to a showdown between lawmakers and U.S. intelligence agencies. According to the Post, Trump’s interaction with the foreign leader included a “promise” that was regarded as so troubling that it prompted the unnamed official to file a complaint with Michael Atkinson, the inspector general of the intelligence community. Atkinson reportedly agreed that the concern was credible and troubling enough to alert congressional oversight committees, but Acting Director of National Intelligence Joseph Maguire has refused to share details of the complaint with lawmakers. Atkinson is scheduled to answer questions in a closed-door session of the House Intelligence Committee today. It’s not clear which world leader’s conversation with Trump prompted the complaint. The Post reports Trump spoke with five world leaders during the time period covered — including Russian President Vladimir Putin and North Korean leader Kim Jong-un.