Washington (CNN) After Britain's ambassador to the US resigned Wednesday following personal attacks by President Donald Trump, one of the most powerful expressions of support for the UK envoy was only 23 words long -- but it spoke volumes, diplomats and foreign envoys said.

A photo tweeted Thursday morning of ambassadors from Germany, France and the European Union with outgoing UK Ambassador Kim Darroch literally showed the other envoys standing shoulder to shoulder with their British counterpart. "Honored to host my colleagues and friends," German Ambassador Emily Haber wrote in her post.

Diplomats from around the world told CNN the image didn't just symbolize solidarity, it also reflected the fact that most embassies have written cables very similar to the private messages -- leaked in an act of political sabotage -- that Darroch had sent to London describing the President and his administration as inept, insecure and incompetent.

I'm honored to host my colleagues and friends from the U.K., France and the European Union for breakfast at my residence this morning. pic.twitter.com/rC9qeiPZFI

Moreover, they said, Darroch was only echoing assessments they hear from both sides of the aisle in Congress and staff inside the White House -- views reflected on TV and in newspapers almost every day.

"The important thing to say is that Ambassador Darroch was not reporting his personal views, he was reporting what people were saying in Washington," said a European official familiar with Washington. "He was reporting things that were being said fairly openly by many Americans in Washington, including on both sides of the political divide."

Darroch's confidential observations -- of a chaotic and divided White House, of a President who fills his speeches with "false claims and invented statistics," of a "diplomatically clumsy" administration that doesn't particularly honor traditional alliances -- weren't just his alone.

"I'm not going to quote from our cables here," one embassy official told CNN, "but you might find similar things."

Darroch's cables didn't reflect only information that diplomats across Washington were picking up from conversations with lawmakers and other sources -- all diplomats work closely with contacts inside the White House. One person familiar with the situation pointed out that the British ambassador was speaking to people who work with Trump every day.

"I don't know that Trump realizes this, but Darroch didn't just invent this stuff," the person said. "It's based on actual conversations with people."

JUST WATCHED Kim Darroch, British ambassador to the US, resigns Replay More Videos ... MUST WATCH Kim Darroch, British ambassador to the US, resigns 01:41

Indeed, in one cable described in the Daily Mail , which first published excerpts from the highly sensitive documents, Darroch is quoted telling the foreign office to make its points to Trump in "simple" and "even blunt" fashion, adding that "as a senior White House adviser told me, there is no upside with this President in being subtle, let alone ambiguous."

At another point, Darroch wrote to his colleagues that "the stories about White House knife fights are, we judge, mostly true: multiple sources and confirmed by our own White House contacts."

'Uniquely dysfunctional'

Darroch, a veteran diplomat who had also served as the UK's national security adviser and its permanent representative to the European Union, added that "this is a uniquely dysfunctional environment."

Diplomats in Washington stressed that the British envoy was just doing his job. One observed that "the President's reaction to the leak just shows you how well observed Darroch's cables were."

According to the Daily Mail, Darroch wrote his colleagues that "for a man who has risen to the highest office on the planet, President Trump radiates insecurity." He also warned about Trump's propensity for outbursts and his use of "sometimes offensive" language.

"There is no filter," Darroch observed.

Trump responded to news of the leak by tweeting that Darroch was "a pompous fool" and a "very stupid guy" who is "not liked or well thought of within the US," a "wacky ambassador" who "I do not know" -- an operatic outpouring of thin-skinned rage that simply validated Darroch's observations, the diplomat said.

The wacky Ambassador that the U.K. foisted upon the United States is not someone we are thrilled with, a very stupid guy. He should speak to his country, and Prime Minister May, about their failed Brexit negotiation, and not be upset with my criticism of how badly it was... — Donald J. Trump (@realDonaldTrump) July 9, 2019

Several diplomats stressed that it's probable that some of the leaked cables were written by staff and signed by Darroch. Either way, they stressed that cables are essential to the work of diplomacy and honest appraisals are key, so that officials in capitals all over the world can formulate sound strategies for dealing with other nations.

"We have to be able to speak bluntly. There can be no restrictions at all. That will not change," explained one current ambassador in Washington, echoing British Prime Minister Teresa May, who told the UK Parliament's House of Commons that "good government depends on public servants being able to give full and frank advice."

Darroch's resignation is a matter of "great regret," May said. Simon McDonald, permanent under secretary at the Foreign and Commonwealth Office, wrote Darroch to say he represented "the best of us" and that he had been "the target of a malicious leak; you were simply doing your job."

On Thursday, Foreign Office minister Alan Duncan told the House of Commons that there is no evidence the leak was a hack and an inquiry is focused on finding out who divulged the information.

'One-way traffic'

The European official familiar with Washington said that "every ambassador in the modern era knows that there is a risk that what you write, however confidential you intended it to be, there's always a risk there will be a leak. You write things in the way you have to write them."

Normally, the official noted, the host country would express its dissatisfaction privately and publicly play the issue down -- as many countries did after the 2010 leak of US diplomatic cables by the organization WikiLeaks.

"Clearly, we know by now this is not the style of President Trump," the official said, pointing out that Trump's attacks on Darroch created a "completely uneven playing field."

"When the President of the United States attacks the British ambassador, the British ambassador has no right of reply. It's one-way traffic," the official said. "There was no way (Darroch) could respond to that or defend himself, first because the cables were confidential."

A State Department spokesperson said Thursday that the US and UK "share a bond that is bigger than any individual, and we look forward to continuing that partnership. We remain committed to the US-UK special relationship and our shared global agenda."