Gregory Korte

USA TODAY

WASHINGTON — House Democrats are investigating whether President Trump's national security adviser violated the emoluments clause of the Constitution by receiving payment from a state-sponsored Russian news outlet.

Lt. Gen. Michael Flynn has appeared on Russia Today and was paid to speak at a Moscow gala hosted by the network in 2015 — a dinner also attended by Russian President Vladimir Putin. As a retired general, he was required by law to obtain advance approval from the Defense and State departments to receive payment from any foreign government. The State Department refused to say Wednesday whether it granted that approval.

The emoluments clause prohibits any federal officer from receiving payment for a foreign country without approval by Congress.

The ranking members of six House committees sent a letter to Defense Secretary Jim Mattis on Wednesday asking him to investigate the issue. And while the consequences are relatively minor — forfeited salary and retirement benefits in the amount of his compensation from the Russian entity — the letter highlights an central line of attack against by Democrats against the Trump White House.

"It is extremely concerning that Gen. Flynn chose to accept payment for appearing at a gala hosted by the propaganda arm of the Russian government, which attacked the United States in an effort to undermine our election, according to U.S. intelligence agencies," said the letter, signed by Rep. Elijah Cummings, D-Md., and five other ranking members. "Even more concerning is that Gen. Flynn, who President Trump has now chosen to be his national security adviser, may have violated the Constitution in the process."

White House press secretary Sean Spicer said there was nothing unusual about the arrangement.

"Gen. Flynn, like countless if not hundreds of flag officers, joins a speaking bureau and gives speeches in numerous places," he said. "The Department of Defense is the appropriate place to review it."

Russian interference in the 2016 presidential election campaign dogged Trump throughout his election and transition, as intelligence agencies have delivered increasingly urgent assessments of Russian efforts to hack emails belonging to the Democratic National Committee and advisers of Trump rival Hillary Clinton.

Last month, the intelligence community highlighted the role that Russia Today played in the Russian propaganda campaign. Flynn has given interviews to the network, and in an interview with The Washington Post last year he compared it to independent U.S. networks CNN or MSNBC.

He said the RT speech in Moscow was "a paid speaking opportunity" arranged through a speaker's bureau.

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