Updated 12 October 2017, 9:50 AEDT
United States President Donald Trump has threatened NBC's broadcast licences because he is not happy with how its news division has covered him.
But experts say his threats are not likely to lead to any action.
The NBC network itself does not need a licence to operate, but individual stations do.
NBC owns several stations in major cities.
Stations owned by other companies such as Tribune and Cox carry NBC's news shows and other programs elsewhere.
Licences come from the Federal Communications Commission, an independent government agency whose chairman is a Trump appointee.
Mr Trump said NBC "made up" a story about the President's plans for the country's nuclear arsenal.
He tweeted that the broadcaster "made up a story that I wanted a 'tenfold' increase in our US nuclear arsenal. Pure fiction, made up to demean. NBC = CNN!"
NBC spokeswoman Hilary Smith had no comment.
The FCC did not respond to messages seeking comment.
Licences are rarely stripped
These days, licence renewals are fairly routine.
A station could be deemed unfit and have its licence stripped if it were telling lies and spreading fake news, as Mr Trump claims.
But Harold Feld of the consumer group Public Knowledge said that was tough to prove.
"The reality is it is just about impossible to make that showing," he said.
"All this stuff is opinion."
As long as someone can demonstrate a reason to believe something is true, it is not a character issue, he said.
Mr Feld said he could recall just two instances in the past 20 years when there had been a renewal challenge.
One involved an owner of radio stations who was convicted of child molestation, and the other when someone died as part of a radio station's contest. Both lost their licences.
Although yanking a licence is rare, just the threat could put pressure on NBC's news coverage.
"The words 'licence renewal' are ones which have had a chilling effect in the past on broadcasters," said lawyer Floyd Abrams, an expert on the First Amendment, citing Richard Nixon's attempts to sway news coverage as president.
"The threat, however unlikely, is one that broadcasters will have to take seriously."
The National Association of Broadcasters, a trade group, said it was contrary to First Amendment principles "for any government official to threaten the revocation of an FCC licence simply because of a disagreement with the reporting of a journalist".
Following his tweet, Mr Trump told reporters in the Oval Office, "It's frankly disgusting the way the press is able to write whatever they want to write and people should look into it".
The President has long railed against mainstream media organisations, deriding them as "fake news".
Political appointees can overturn judge's decision
FCC chairman Ajit Pai is a Trump appointee, but experts say he cannot pull a licence just because he feels like it.
Renewals come up every eight years, and challenges are heard by an administrative law judge.
The judge's decision can be overruled by political appointees at the FCC, however.
And the agency could start a special proceeding to revoke a licence, said Erwin Krasnow, former general counsel of the National Association of Broadcasters.
Even so, Mr Krasnow said a challenge was unlikely because of the First Amendment and because the Communications Act governing the FCC does not allow for censorship.
Mr Pai's past statements also suggest he would not use the agency's powers to regulate news coverage.
In a September speech, Mr Pai noted that while people want the FCC to take action against cable news channels like Fox News, MSNBC, or CNN because they disagree with the coverage, "these demands are fundamentally at odds with our legal and cultural traditions".
Mr Feld, who is a frequent critic of Mr Pai, said the chairman is a fan of deregulation and "the last person in the world who would want to revive the licence challenge process".
"NBC can sleep easy knowing Ajit Pai is chair," he said.