Donald Trump called Theresa May "weak" and Angela Merkel "stupid" in a phone calls to the German and then UK leader, according to a bombshell new report.
Two sources have also claimed Mr Trump often so unprepared and "outplayed" in conversations with world leaders that senior White House officials feared he posed a danger to the national security of the US, two sources have claimed.
According to a CNN report published on Monday by the Watergate journalist Carl Bernstein, Mr Trump's former top officials including national security advisers HR McMaster, Defence Secretary John Bolton, Secretary of State Rex Tillerson and White House Chief of Staff John Kelly, determined that the President was often "delusional" in his dealings with foreign leaders.
CNN's sources said Mr Trump was more focused on achieving his personal agenda than discussing matters of national interest and he would attempt to "either charm, jawbone or bully" foreign leaders into agreeing with him.
The US President was reportedly more aggressive with female heads of state, with sources claiming Mr Trump called former UK Prime Minister Theresa May "weak" and telling her she lacked courage.
He was also reportedly tough on German Chancellor Angela Merkel.
A source said: "Some of the things he said to Angela Merkel are just unbelievable: he called her 'stupid' and accused her of being in the pocket of the Russians.
"He's toughest [in the phone calls] with those he looks at as weaklings and weakest with the ones he ought to be tough with."
A German official source told CNN that special measures were taken in Berlin to ensure the calls remained secret.
The majority of Mr Trump's calls were with Turkish President Recep Erdogan and Emmanuel Macron, as the French President reportedly tried to get Mr Trump to change his policy on environmental and security matters.
In his conversations with Vladimir Putin and Mr Erdogan, the sources say Mr Trump often spoke badly of former Presidents George W Bush and Barack Obama. At one point Mr Trump said "they didn't know BS" when speaking of the two former heads of state, said the sources.
CNN did not reveal the job titles of the two sources but Mr Bernstein explained that they were repeatedly interviewed over a four-month period.
The sources, along with other officials, either directly listened to the President's phone calls or were provided detailed summaries after they were completed.
Mr Kelly, Mr McMaster, Mr Mattis and Mr Tillerson have not responded to CNN's requests for a comment.
After publication of the report, White House Deputy Press Secretary Sarah Matthews said: "President Trump is a world class negotiator who has consistently furthered America's interests on the world stage.
"From negotiating the phase one China deal and the USMCA to NATO allies contributing more and defeating ISIS, President Trump has shown his ability to advance America's strategic interests."
It comes after reports Mr Trump had learned in March that Russia had offered the Taliban bounties to kill US troops in Afghanistan.
The White House issued a statement on Saturday denying that Mr Trump or Vice President Mike Pence had been briefed on such intelligence.
“This does not speak to the merit of the alleged intelligence but to the inaccuracy of the New York Times story erroneously suggesting that President Trump was briefed on this matter,” Press Secretary Kayleigh McEnany said.
CNN's sources claimed the US President spoke with his Russian counterpart about Mr Trump's desire to end the American military presence in Afghanistan but they did not speak about Taliban bounties.
John Bolton, a former national security adviser who was forced out by Mr Trump last September and has now written a tell-all book about his time at the White House, said that “it is pretty remarkable the president’s going out of his way to say he hasn’t heard anything about it, one asks, why would he do something like that?”
Mr Bolton told NBC’s “Meet the Press” that he thinks the answer “may be precisely because active Russian aggression like that against the American service members is a very, very serious matter and nothing’s been done about it, if it’s true, for these past four or five months, so it may look like he was negligent.
“But of course, he can disown everything if nobody ever told him about it.”
Mr Bernstein points out in his report about Mr Trump's phone calls that the tone of conversations described by the White House sources is consistent with some claims made in Mr Bolton's book.