Former National Security Adviser Michael Flynn worked as a “foreign agent” for the Turkish government last fall, even as he served as a top adviser to Donald Trump’s campaign—and failed to disclose his lobbying efforts as required by law. The revelation came in a retroactive filing by Flynn with the Justice Department on Tuesday. It reveals he was paid more than a half-million dollars to lobby on behalf of a firm linked to the Turkish government. By failing to register with the federal government, Flynn violated the Foreign Agent Registration Act. On Election Day, Flynn authored an op-ed in the newspaper The Hill calling for the extradition to Turkey of a prominent opponent of President Recep Tayyip Erdogan who’s lived in Pennsylvania since 1999. At the White House, Press Secretary Sean Spicer was asked if Donald Trump knew of Flynn’s work as a foreign agent.

Press Secretary Sean Spicer: “I don’t believe that that was known. I would refer you to General Flynn and to the Department of Justice in terms of the filings that have been made.”

John Roberts: “Had the president have known that, would he have appointed him?”

Press Secretary Sean Spicer: “I don’t know, John. That’s a hypothetical that I’m not prepared to ask. I don’t—I don’t—I don’t know what he discussed prior to—prior to being appointed, in terms of his background, his résumé, his client base. I don’t know any of that.”

Last month, the White House fired Michael Flynn as national security adviser, following revelations he discussed U.S. sanctions against Russia with the Russian ambassador before Donald Trump’s inauguration.