Donald Trump threatens to shut down NBC and other TV news networks that criticise him

It's unlikely, however, that revoking network licenses would be an easy task

Donald Trump has threatened to shut down NBC and other American networks, saying that they peddle fake news.

"With all of the Fake News coming out of NBC and the Networks, at what point is it appropriate to challenge their License? Bad for country!" Mr Trump wrote in a tweet.

Mr Trump's tweet came in response to a story written by NBC, which said that Mr Trump had sought to increase America's nuclear arsenal tenfold after taking a look at a briefing slide that showed steady reduction of the US nuclear arsenal since the 1960s. The story cited three officials who were reportedly in the room when Mr Trump made the comments.

"Fake @NBCNews made up a story that I wanted a 'tenfold' increase in our US nuclear arsenal," Mr Trump had tweeted before his threat. "Pure fiction, mad eup to demean. NBC = CNN!"

The President has regularly targeted news networks critical of him since January, when he gave a press conference as President-elect and shouted down a CNN reporter as "fake news". The term - which Mr Trump says he invented but had been used frequently before to describe the proliferation of stories written by anonymous bloggers to spread lies during the 2016 election - has since become one of his go-to insults when the media publishes critical coverage of the Trump administration.

The report about Mr Trump's nuclear arsenal said that the joint chiefs of staff and Secretary of State Rex Tillerson all pushed back on the nuclear ambitions, and that Mr Tillerson later called the President a "moron" following the meeting. Mr Tillerson last week refused to confirm that he had called the President that, and Mr Trump has said that those reports are fake news. During an interview, the President also said that he would have to compare IQ scores with Mr Tillerson if his secretary had actually made the remarks.

It isn't clear that Mr Trump would be able to easily revoke broadcast licenses for any of the major networks simply because he disagrees with the content they air, however.

Neither NBC or ABC released statement following the tweet, but others in government stepped in to comment on the issue. Democratic Senator Ed markey wrote to FCC chairman Ajit Pai Wednesday, urging him to resist requests from the President to revoke licenses because of coverage.

"It is inappropriate for the President to propose challenging broadcasters' licences because he disagrees with their coverage," that letter read. "The First Amendment is the cornerstone of our democracy, and the news media plays an instrumental role in educating the American public and holding elected officials accountable. Any insinuation that elected officials could use the levers of government to control or sensor the news media would represent a startling degradation of the freedom of press."

The Federal Communications Commission (FCC), which oversees licensing - notably, it licenses individual broadcast stations, not to networks specifically - is an independent agency in the federal government, and isn't required to follow orders directly from the White House as would branches of the executive like the Department of Justice, for instance. While the commissioners of the FCC are appointed by the President and approved by the Senate, the agency's relative independence is there by design to push back on situations where someone in the executive branch would attempt to dampen the free speech protections provided to licensed broadcasters.

Mr Trump's comments came just one day after an American reporter was sentenced to prison in a Turkish court, where she was convicted of terrorist propaganda charges. That imprisonment was widely seen as highlighting the increased targeting of journalists in that country, which has been scrutinized for President Recep Tayyip Erdogan's government crackdown on media freedoms.

Responding to Mr Trump's musing about revoking licenses for broadcast networks critical of him, former US federal Prosecutor and frequent Trump critic Preet Bharara called the President childish.

"Adult daycare shift alert," Mr Bharara tweeted. "Please report for duty."

It wasn't immediately clear if Mr Trump intended to threaten cable news networks as well, which are regulated differently than their broadcast counterparts.