Donald Trump. Richard Drew/AP Photo; Win McNamee/Getty Images President Donald Trump tweeted on Thursday morning to ask the Senate Intelligence Committee, which is investigating Trump's possible collusion with Russia in the 2016 election, to instead look into "Fake News Networks."

"Why Isn't the Senate Intel Committee looking into the Fake News Networks in OUR country to see why so much of our news is just made up-FAKE!" Trump tweeted.

Trump's tweet continues a media offensive that began Wednesday morning when NBC News reported that Secretary of State Rex Tillerson had called Trump a "moron" over the summer.

Tillerson held a press conference Wednesday in which he said Trump "is smart," though he did not explicitly deny having called him a moron. Instead, he dismissed the report as "nonsense" that he would not address.

"The @NBCNews story has just been totally refuted by Sec. Tillerson and @VP Pence. It is #FakeNews," Trump tweeted on Wednesday.

"It was fake news — it was a totally phony story," Trump told reporters during a visit to Las Vegas to meet some of the victims of Sunday night's mass shooting. "It was made up by NBC. They just made it up."

A representative for Tillerson did later explicitly deny the "moron" quip, but NBC News told Business Insider that it stood by its reporting.

According to the latest statement by Senate Intelligence Committee leaders, "the issue of collusion" between the Trump campaign and Russia "is still open." Additionally, an obstruction-of-justice case may be building against Trump after he fired the head of the FBI while the bureau investigated his campaign.

The committee on Wednesday also acknowledged the propaganda, or disinformation, that infiltrated US social-media networks before the election. Large tech companies like Facebook, Google, and Twitter have struggled lately at preventing their products from distributing fake news, but it's unclear whether Trump meant to include these companies in what he called "Fake News Networks."