Subscribe for 99¢

Kim Darroch, Britain’s ambassador to the United States, resigned his post Wednesday, after his leaked criticism of President Donald Trump prompted a presidential meltdown worthy of a toddler. It isn’t going to cause markets to tumble or fighter jets to scramble, but it provides another reminder of a dangerous reality that has roiled our domestic politics and now strains our global alliances: This nation is led by a man who is temperamentally unfit for the job.

A core part of any ambassador’s responsibility is to provide his or her government with unvarnished assessments of what’s happening within the leadership of other governments, even close allies.

Darroch, who is by all accounts a seasoned and capable diplomat, was doing just that in communications to his superiors in London. In messages intended to remain private, he warned that Trump is “inept” and “radiating insecurity,” that the administration is beset by “vicious infighting and chaos,” and that its Iran policy is “incoherent.”

Harsh? Yes — but the ability to be blunt with the home office is crucial in that line of work. And anyone who has taken a clear-eyed look at this administration’s approach to foreign affairs can hardly argue with adjectives like “inept” and “incoherent.”

The problem wasn’t Darroch’s frankness; it was the still-unknown malicious parties that obtained and leaked those memos publicly. It was an unfortunate development that, in normal times, would have left both nations’ governments red-faced but issuing carefully worded statements reiterating their joint commitment to their alliance.

In fact, the U.S. State Department offered such a statement, noting that the “incredibly special and strategic relationship with the United Kingdom ... has gone on for quite a long time and it’s bigger than any individual.” But this was only after Trump himself had already reminded the world that he is emotionally incapable of that kind of selfless statesmanship.

In one of his typical Twitter eruptions, Trump called Darroch “wacky,” a “very stupid guy” and a “pompous fool” — this while acknowledging he doesn’t know him — and declared: “We will no longer deal with him.”

It’s difficult to overstate how abnormal this kind of thin-skinned personalization is in diplomatic affairs. One veteran British diplomat told Parliament he’d never in his 37-year career seen any head of state, let alone a close ally, refuse to deal with a specific British ambassador.

Darroch resigned after Boris Johnson, the Trump-like Conservative Party populist who is likely to become Britain’s next prime minister, refused to support the ambassador. That prompted a Labour Party official to seethe: “Just imagine Churchill allowing this humiliating, servile, sycophantic indulgence of the American president’s ego to go unchallenged.”

To which we might add: Just imagine FDR — or Truman, or Reagan, or any other president in modern times — straining our closest alliance in service to his own petty insecurity.