NBC News reporters have no plans to back down from President Trump, no matter how many times he calls them "fake news."

Early Thursday morning, President Trump unleashed another fiery Twitter assault against the network after a story published on Wednesday reported that Secretary of State Rex Tillerson called Trump a "moron" and threatened to resign during a meeting at the Pentagon in July.

In a pair of early-morning tweets, Trump called NBC News "fake news," a moniker he typically reserves for CNN, and suggested the Senate Intelligence Committee should investigate the network for what he deemed "made up" news reports.

On Wednesday, in a hastily arranged press conference, Tillerson pushed back against the report but refused to deny several key points made by the story. He also avoided denying that he called Trump a moron, casting questions about it aside as "petty stuff." Following the press conference, State Department spokeswoman Heather Nauert denied Tillerson called Trump a "moron," and Vice President Mike Pence said in a statement, "Any reporting to the contrary is categorically false."

Despite that, NBC News correspondent and MSNBC anchor Stephanie Ruhle, one of four reporters who worked on the Tillerson story, offered an impassioned defense of her team's reporting, and went after Trump specifically after he complained the network didn't verify their report with him.

"Sir, we didn't need you to verify that he called you a moron," Ruhle said. "He did it behind your back."

It was the second day in a row Ruhle appeared on MSNBC to defend NBC News' reporting. On Wednesday, Ruhle, who was in Las Vegas reporting on the massacre, told her college Hallie Jackson on MSNBC, "My source didn't just say that he called him a moron. He said an f-ing moron."

NBC national political reporter (and noted Philadelphia Eagles fan) Carol E. Lee also publicly defended the report's accuracy, and said Trump's fiery rebukes are a way to avoid accepting the damning facts of the story.

"If the president were to accept our reporting as true, which it is, he would essentially have to fired Rex Tillerson," Lee said, adding that NBC News worked with the White House on the story, and that one official even confirmed Pence has had repeated conversations with Tillerson about showing more respect to the president.

NBC News isn't alone in reporting on Tillerson's unease about working for Trump. On Thursday, the New York Times reported that allies close to Tillerson, including Defense Secretary Jim Mattis and White House chief of staff John F. Kelly, had to talked him out of drafting a letter of resignation several times. Sources told the Times that Tillerson has also "regularly expressed astonishment at how little Mr. Trump understands the basics of foreign policy."

That point was underscored on Wednesday by Sen. Bob Corker (R., Tenn), the chairman of the Foreign Relations Committie, who told reporters in shockingly candid terms, "I think Secretary Tillerson, Secretary Mattis and Chief of Staff Kelly are those people that help separate our country from chaos, and I support them very much."

There have also been public signs that a rift has formed between Tillerson and Trump. Last week, the president undercut Tillerson on Twitter by saying the secretary of state is "wasting his time" attempting to negotiate with North Korea. After the president's much-maligned comments about Charlottesville, Tillerson pointedly separated himself and the State Department on Fox News by repeatedly stating, "The president speaks for himself."

To Trump's request that NBC News should apologize to everyone for the story, MSNBC host Hallie Jackson offered a pointed retort.

"It's safe to say NBC News will not be issuing an apology to America," Jackson said.