LONDON — The British ambassador to the United States described the White House as “uniquely dysfunctional,” told his counterparts back home that President Trump was “inept” and “insecure,” and warned that his administration could collapse in “disgrace.”

In a cache of leaked diplomatic cables dating from 2017 to the present, Sir Kim Darroch worried Trump might be in debt to “dodgy Russians.” He also said that Trump could wreck the world trade system and that his administration might go to war with Iran.

In one cable, the ambassador wrote: “We don’t really believe this Administration is going to become substantially more normal; less dysfunctional; less unpredictable; less faction riven; less diplomatically clumsy and inept.”

Excerpts from the briefs and memos were published late Saturday by the Mail on Sunday, a British tabloid, under a banner headline that described the cache of documents as a “bombshell.”

President Trump criticized Kim Darroch on July 7 in Morristown, N.J., after leaked memos showed Darroch called Trump's administration "inept" and "insecure." (Reuters)

The British news media, including the BBC, then picked up the news.

The British Foreign Office called the leak “mischievous.” A British official, who requested anonymity because of the sensitivity of the matter, confirmed the authenticity of the cables.

“The British public would expect our ambassadors to provide ministers with an honest, unvarnished assessment of the politics in their country,” the Foreign Office said in a statement.

“Their views are not necessarily the views of ministers or indeed the government. But we pay them to be candid. Just as the U.S. ambassador here will send back his reading of Westminster politics and personalities.”

Foreign Office officials were signaling that diplomats the world over send their home offices bits of color, news clippings, gossip and analysis.

Trump, speaking to reporters Sunday afternoon, said “the ambassador has not served the U.K. well.”

“We’re not big fans of that man,” he said.

Darroch, ambassador to the United States since January 2016, also warned his counterparts not to underestimate Trump.

“Do not write him off,” he wrote. Though “mired in scandal,” Trump could “emerge from the flames, battered but intact, like Schwarzenegger in the final scenes of ‘The Terminator.’ ”

The frank assessment was sent to officials in Prime Minister Theresa May’s government. The Mail newspaper named only one recipient: Mark Sedwill, May’s national security adviser.

May and Trump have had a fractious relationship, with the president alternately praising the outgoing prime minister’s grit and insulting her as a weak negotiator. 

In one memo, Darroch referred to “knife fights” between British diplomats and the Trump team.

Trump has often said he could have won a better deal for Britain’s exit from the European Union. In one exchange, Trump suggested May “sue” the trade, travel and security bloc in which Britain remains a member. May suggested she thought the idea was funny.

Relations between Trump and 10 Downing Street, however, appeared to be on the upswing since Trump’s official state visit in June, when he visited England to dine with Queen Elizabeth II and commemorate the 75th anniversary of the Allied forces’ D-Day assault on the Germans in France.

After all the pomp and circumstance, Trump said, “There are those that say they have never seen the queen have a better time, a more animated time.”

In one of his notes home, the British ambassador praised the trip, writing that the White House and Trump were “dazzled” by their reception.

“These are close contacts, with whom we have spent years building relationships: These are the gatekeepers and the ‘Trump whisperers,’ the people we rely upon to ensure the U.K. voice is heard in the West Wing,” Darroch wrote.

May is on the way out, pushed from power by her own Conservative Party over her failure to deliver Brexit. She is most likely to be replaced by former London mayor Boris Johnson, for whom Trump has expressed admiration.

Darroch called the 2017 White House “a uniquely dysfunctional environment.”

“We could also be at the beginning of a downward spiral, rather than just a roller coaster: something could emerge that leads to disgrace and downfall.”

The author of the Mail scoop is political journalist and commentator Isabel Oakeshott, who wrote an unauthorized biography of former prime minister David Cameron and was the ghostwriter behind the book “The Bad Boys of Brexit,” by Arron Banks, one of the main financial backers of the June 2016 referendum campaign to leave the European Union.

After Darroch’s wires were published, Brexit campaigner and Trump ally Nigel Farage said the British ambassador should be fired. 

“Kim Darroch is totally unsuitable for the job and the sooner he is gone the better,” Farage tweeted.

Toluse Olorunnipa in Morristown, N.J., contributed to this report.