Updated at 4:50 p.m. ET

White House press secretary Sean Spicer said Tuesday that reports that Jared Kushner asked Russia about setting up a secret line of communication with Moscow were based on "facts that are not substantiated," but he did not explicitly deny the allegations.

Instead, in the first press briefing since President Trump returned from a nine-day trip abroad, Spicer focused on the fact that The Washington Post story, which first reported the request, used anonymous sourcing.

When pressed on whether the president would approve of such a back channel with Russia, Spicer said, "You're asking if he approves of an action that is not a confirmed action."

He added that Secretary of Homeland Security John Kelly and National Security Adviser H.R. McMaster have both discussed that "in general terms, back channels are an appropriate part of diplomacy."

NPR has not independently confirmed the claims made in The Post's story, which cites "U.S. officials briefed on intelligence reports."

The article describes a Dec. 1 or 2 meeting in which Kushner, Trump's son-in-law and adviser, discussed setting up a direct communication system between Trump and Moscow with the Russian ambassador to the U.S. The meeting was also attended by former national security adviser Michael Flynn, but both Kushner and Flynn were still just private citizens at the time.

Spicer also said the president is meeting Tuesday afternoon with two more candidates to replace James Comey for FBI director: John Pistole, a former TSA administrator who previously served as FBI deputy director, and Chris Wray, a former Justice Department official who served during the George W. Bush administration.

Reports continue to circle about other impending White House staff changes, and the briefing followed news Tuesday morning that communications director Michael Dubke had resigned.

"I think [President Trump] is very pleased with the work of his staff," said Spicer. "I think he is frustrated, like I am, and like so many others, to see stories come out that are patently false. To see narratives that are wrong. To see 'fake news.' "

CNN's Jim Acosta, who has notably sparred with Trump over the concept of "fake news," pressed Spicer for an example. The press secretary cited a tweet from over the weekend, and reporters pushed back again. Watch the exchange:

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