After a combative press conference on Thursday, in which he railed at "fake news", bullied reporters and dismissed facts, the president took to Twitter on Friday to continue his assault on the press.
"The FAKE NEWS media (failing @nytimes, @NBCNews, @ABC, @CBS, @CNN) is not my enemy, it is the enemy of the American People!," he declared.
— Donald J. Trump (@realDonaldTrump) February 17, 2017
He had initially only name-checked The New York Times, CNN and NBC News, but he deleted the first tweet to add ABC and CBS.
While the phrase "enemy of the people" goes as far back as the Roman Empire, Russia's Joseph Stalin and Mao are among the leaders to have made the term infamous in more modern history.
"Charming that our uneducated President manages to channel the words of Stalin and fails to hear the historical resonance of this phrase," tweeted Mitchell Orenstein, professor of Russian and East European studies at the University of Pennsylvania.
"What it basically meant was a death sentence," he told Voice of America.
Charming that our uneducated President manages to channel the words of Stalin and fails to hear the historical resonance of this phrase https://t.co/TuoCkMVwKa
— Mitchell Orenstein (@m_orenstein) February 17, 2017
Among those shocked by the expression was Tom Malinowski, former assistant secretary of state for democracy, human rights and labour. "As an American diplomat, I stood up to petty tyrants who called journalists 'enemies of the people. Guess that's not our policy anymore," he tweeted.
Eliot A Cohen, counsellor to former Republican Secretary of State Condoleezza Rice, said: "The language of an aspiring tyrant. And no, not a joke, and not an exaggeration, and not a thought spasm from a disordered intellect."
The language of an aspiring tyrant. And no, not a joke, and not an exaggeration, and not a thought spasm from a disordered intellect. https://t.co/8PWdLGnok8
— Eliot A Cohen (@EliotACohen) February 17, 2017
The expression was also a favourite of Mao, who died in 1976. The Chinese leader, who quoted the term to denounce anyone who criticised his policies, created the Great Famine that killed an estimated 36 million Chinese.
When David Axelrod, former chief strategist for Barack Obama, noted on Twitter that no other president would have used the term, Li Yuan, a journalist in China, pointed out: "Chairman Mao had. Every dissenting voice was "the enemy of the people" under Mao."
Chairman Mao had. Every dissenting voice was "the enemy of the people" under Mao. https://t.co/7jftRMmXOT
— Li Yuan (@LiYuan6) February 18, 2017
"He's got his style," Congressman Ted Yoho, a Republican on the House Foreign Affairs Committee, told CNN in response to the provocative phrase. "Things will adjust," he predicted.
Mr Trump is not the first US president to criticise the media.
Thomas Jefferson railed against newspapers as "polluted vehicles" of falsehood and error. Richard Nixon tangled with reporters in the toxic atmosphere of Watergate, considering them the "enemy." Bill Clinton publicly condemned "purveyors of hatred and division" on the public air waves.
But historians are hard-pressed to find anything that approaches the all-out attack on the media that Mr Trump seems intent on escalating at every turn.
"There has never been a kind of holistic jihad against the news media like Trump is executing," said Rice University historian Douglas Brinkley. "Trump is determined to beat and bloody the press whenever he finds himself in a hole, and that's unique."