President Donald Trump has called the U.S. media, the enemy of the American people. Trump had hurled the accusation in a tweet which he had then quickly deleted. Trump has been steadily building up on the anti-media rhetoric that was central to his campaign messaging.

Mr Trump has referred to unfavourable coverage by the media as "fake news", but for many journalists, the accusation that they were "the enemy of the American people" crossed a line.

David Frum, a former speechwriter for George W Bush and a senior editor at The Atlantic, said that the comment looked "a lot like an incitement to vigilante violence". "I think we are seeing here just a violation of every decent democratic, constitutional norm we ever thought the leaders of the country should be guided by," he said.

Rice University historian Douglas Brinkley said that Mr Trump is unique among US presidents with his attacks on the press. "There has never been a kind of holistic jihad against the news media like Trump is executing," he said. "Trump is determined to beat and bloody the press whenever he finds himself in a hole."

Princeton historian Julian Zelizer agreed and said, "The scale and scope of this is unlike anything that we've seen in the past." The closest parallel might be with Richard Nixon, who told the chairman of the Joint Chiefs of Staff in a taped conversation that "the press is your enemy".

In 1807, President Thomas Jefferson wrote to an editor in terms that Mr Trump might approve, "Nothing can now be believed which is seen in a newspaper. Truth itself becomes suspicious by being put into that polluted vehicle."

But that was a far cry from what he wrote in 1787 before he became president. "Were it left to me to decide whether we should have a government without newspapers, or newspapers without a government, I should not hesitate a moment to prefer the latter."

More recently, during his presidential campaign in 2000, George W Bush was overheard saying about a New York Times reporter as a "major league asshole".

By Premji