DONALD TRUMP‘S decision to sack James Comey as FBI director on May 9th seemed to many like a defining moment in his chaotic early stab at governing. Even some Republicans wondered whether it could spell the beginning of an early end to Mr Trump’s crisis-ridden presidency. But already that looks like last week’s story—following claims, first published by the Washington Post on May 15th, that Mr Trump divulged highly classified information to Russia’s foreign minister and ambassador to Washington, DC, in the Oval Office.

Even the fact of the meeting between the president and, respectively, Sergei Lavrov and Sergey Kislyak, had previously looked bad for Mr Trump. It took place the day after he sacked Mr Comey at least partly, Mr Trump himself suggested, because he disapproved of an FBI counter-espionage investigation into Russia’s effort to rig the election last year, with alleged assistance from one or two of the president’s then associates. The meeting was off-limits to American media; the Russian delegation included a photographer for the state-owned news agency, which mischievously released photographs showing the president and his guests getting along like old pals.

Perhaps it was that beguiling bonhomie that made Mr Trump, if the Post’s and subsequent reporting of the meeting is accurate, blunder so heinously. Citing serving intelligence officers, among other sources, the Post alleged that Mr Trump boasted to the Russians of his knowledge of an impending terrorist threat from Islamic State. “I get great intel. I have people brief me on great intel every day,” he is alleged to have said.

He is then reported to have divulged details of the threat, which had been provided to America’s spies by an allied intelligence agency, including details of the Middle Eastern city in which it was uncovered. According to the Post’s sources, these “disclosures jeopardised a critical source of intelligence on the Islamic State”.

The Post’s sources underlined the sensitivity of the intelligence Mr Trump had allegedly bragged of knowing about. “This is code-word information,” an unnamed official allegedly told the newspaper. Mr Trump “revealed more information to the Russian ambassador than we have shared with our own allies”.

The White House’s spin team, which has previously been caught flat-footed by Trump-induced scandals, rushed to try to put out the impending firestorm. In an allegedly fraught response (journalists at the White House reported hearing shouting emanating from a room where Mr Trump’s spokesman Sean Spicer and his deputy Sarah Huckabee Sanders were holed up with Stephen Bannon, the chief strategist) the administration released statements from several officials rebutting the Post’s report.

“The story that came out tonight as reported is false,” said H.R. McMaster, the respected national security adviser, in a brief appearance outside the White House, during which he read a short statement and took no questions from the assembled journalists. “At no time were intelligence sources or methods discussed and the president did not disclose any military operations that were not already publicly known.”

It must be hoped, for the sake of American and global security, that Mr Trump has indeed been maligned. Yet Mr McMaster’s choice of words sounded oddly legalistic. Denying the veracity of “the story…as reported” suggested he might be leaving himself room, at some later time, to acknowledge that, even if some of its details were false, the Post’s main allegation—that Mr Trump had leaked sensitive intelligence—was accurate.

Moreover, the Post and, hot on its heels, the New York Times and Reuters, which made much the same allegation against the president, did not claim that Mr Trump had leaked intelligence sources or methods to his country’s implacable adversary. They alleged that the president had leaked classified details to the Russians from which those sources and methods might perhaps be extrapolated.

In subsequent tweets, Mr Trump raised further doubt about the rebuttals his senior officials had been sent out to make on his behalf. "As president I wanted to share with Russia," he wrote, "facts pertaining to terrorism and airline flight safety." He had an "absolute right" to do this, he declared, "as president". That is perfectly true, but possibly not the main point.

If Mr Trump really did shoot his mouth off to the friendly Russians, he probably broke no law. The president can choose to “declassifiy” almost whatever intelligence he sees fit.

But that scarcely minimises the gravity of the allegation against him. In the view of Alan Dershowitz, a legal scholar, it is “the most serious charge ever made against a sitting president of the United States”.

If the Post’s account is substantially correct, Mr Trump put lives at risk in Syria and jeopardised a source of intelligence that was considered a possible means to keep Americans safe. According to the Post, the “information the president relayed had been provided by a US partner through an intelligence-sharing arrangement considered so sensitive that details have been withheld from allies and tightly restricted even within the US government.” That, in turn, almost incredibly, would suggest Mr Trump may have undermined America’s credibility as an intelligence partner.

If the White House cannot kill the allegation—and so far it has not—further details of Mr Trump’s alleged blunder seem likely to emerge. It was allegedly relayed to the CIA and National Security Council by anxious White House officials after they considered the possible damage the president had done. The fact that it was then leaked to journalists shows the apparently irredeemable collapse in relations between the Trump administration and some senior American spies. Among previous intelligence-related scandals, leaked to the press by angry or worried spooks, three concerned surreptitious conversations between Mr Kislyak and senior Trump advisers. One led to Mike Flynn’s removal as national security adviser and another to Jeff Sessions, Mr Trump’s attorney-general, being forced to recuse himself from the FBI’s Russia probe (though not, it seems, from playing a role in sacking Mr Comey). Further damaging leaks seem inevitable, which, among other things, suggests that if the president really was trying to shut down the Russia investigation, he will fail.

The response to the Post report by some Republican congressmen, in whose hands rests the fate of two separate congressional investigations into, in effect, Mr Trump and Russia, suggests more bad news for the president. Bob Corker, the respected chairman of the Senate foreign relations committee, with whom Mr Trump was until recently on good terms, described the administration as being in a “downward spiral”.

A spokesman for Paul Ryan, the hitherto supplicant Speaker of the House of Representatives, said he was awaiting a “full explanation” of the alleged leak to the Russians from the White House. Perhaps Mr Ryan may come to regret a statement he released last year on learning that the FBI had no plans to prosecute Hillary Clinton, Mr Trump’s vanquished opponent, for the alleged crime of maintaining a private e-mail account for her work as secretary of state. “Declining to prosecute Secretary Clinton for recklessly mishandling and transmitting national security information will set a terrible precedent,” Mr Ryan thundered.

The accumulative damage that Mr Trump is doing to America’s governing norms, it appears, has a counterpart in the damage he is doing, day by day, to his standing within the government and on the Hill, including among senior Republicans. The president never had many sincere supporters among elected Republicans. They backed him in fear of a vindictive tweet and the hope that he would sign conservative bills into law. But with the president’s approval rating plummeting and a diminishing prospect of the sorts of health-care and tax reforms they once dreamed of, both fear and hope are giving way to exasperation and contempt.

Before this latest scandal, the president was looking forward to putting his troubles behind him on his first overseas trip; he is due to visit Saudi Arabia and Israel later this week, before attending meetings of NATO and the G7 in Belgium and Italy. But the Post’s allegations, if not disproved, seem likely to travel with him.

Even before Mr Trump’s inauguration, in January, Israeli officials were reported to be concerned that his administration could not be trusted with sensitive material. According to Haaretz, an Israeli newspaper, they feared “the exposure of classified information to their American counterparts under a Trump administration could lead to their being leaked to Russia and onward to Iran”.

Editor’s note: This piece was updated at 1.00pm London on May 16th to include Mr Trump’s reaction on Twitter to the allegations.