President Trump came out forcefully against the claims, writing on Twitter that the story was "pure fiction" and "made up to demean".
Trump's "comments raised questions about his familiarity with the nuclear posture and other issues".
Trump's advisers, including the Joint Chiefs of Staff and Secretary of State Rex Tillerson, were surprised, according to the network.
Russia's TASS news agency quoted North Korean Foreign Minister Ri Yong Ho as saying: "With his bellicose and insane statement at the United Nations, Trump, you can say, has lit the wick of a war against us".
Arms-control experts maintain that an increase in United States arms would spur another arms race with Russian Federation and most likely China and could lead to other countries seeking nuclear capabilities.
WH on Trump's Tillerson Comment'It Was a Joke
"This kind of erroneous reporting is irresponsible", Mattis said in a written statement.
The threat provoked widespread anger on social media and elsewhere with many attacking the president for directly challenging the First Amendment, which guarantees the freedom of the press.
"At that July 19 meeting, according to senior administration officials, Trump asked military leaders to fire the commander of USA forces in Afghanistan and compared their advice to that of a NY restaurant consultant whose poor judgment cost a business valuable time and money", according to NBC'sreport.
Noting that Trump greatly benefits from a free press, the Reliable Sources host explained that Trump tends to rip "fake news" when the White House is underperforming. Today, Donald Trump has threatened to do the same to NBC.
The NBC report comes during a time of high tension between the United States and North Korea over Pyongyang's nuclear weapons and missile programs, and just ahead of an expected announcement from Trump on whether to decertify the global deal on Iran's nuclear programme.
Sen. Dianne Feinstein announces she's running for reelection
Congressional Republicans and President Trump have, however, called for a review of federal policy that now permits bump stocks. California's increasingly progressive political environment has left more "moderate" Democratic candidates on the defense.