London (CNN) The UK is currently mired in a wild international crisis, most probably of its own making.

On Sunday, scathing comments about US President Donald Trump made in leaked diplomatic cables by Britain's ambassador to the US, Kim Darroch, were published in a British newspaper.

In the messages, Darroch called the leader of the free world "inept," "insecure," and "incompetent." He said that Trump's career could "end in disgrace" and even said of alleged collusion with Russia that "the worst cannot be ruled out."

He continued to attack Darroch on Tuesday : "The wacky Ambassador that the UK foisted upon the United States is not someone we are thrilled with, a very stupid guy ... I don't know the Ambassador but have been told he is a pompous fool."

This whole situation is very weird. A diplomatic service relies on senior diplomats -- and there are few more senior in the UK than our man in DC -- being able to speak their minds, providing what they believe to be accurate, fact-based assessments, and speaking truth to power. That is certainly what Darroch, a career diplomat and not a political appointee, would have assumed to be the case when writing back to London.

And while a lot of attention will be given to the ferocious response from Trump to America's supposed best friend, the more troubling story here is the political meltdown that has taken place in London.

"The ambassador, believe it or not, can get by very easily without having to meet the president at all," Christopher Meyer, a former British ambassador to the US told CNN. "If I were Sir Kim though, I would be more worried about those in London who are determined to do him down."

There are very few in London, including Meyer, who think that this leak was anything more than a politically-motivated hit job on Darroch -- a diplomat who cannot defend himself.

Exactly what those motives are remains unclear but, frankly, there are so many moving parts in British politics at the moment that it could be anything.

First, there's the race to replace Theresa May as Prime Minister. The final two candidates are frontrunner Boris Johnson, the former foreign secretary, and Jeremy Hunt, the current foreign secretary. Hunt has had to publicly comment on this story in his role as the UK's top diplomat. He has had to walk a tightrope of not criticizing Darroch, while not alienating the most powerful man on earth. Johnson, by contrast, is under no obligation to speak.

Then there's the broader culture war the UK is living through. Brexit (remember that) has both rocked the UK's political system so hard that it's barely recognizable and simultaneously paralyzed politics.

Every political conversation begins and ends with Brexit -- and usually goes absolutely nowhere useful.

Over the course of the past three years, this has veered from polite disagreement between leavers and remainers to unedifying bitterness.

Some Brexiteers think that the civil service has been involved in an establishment stitch-up to make leaving the EU as hard as possible, and that Theresa May has been complicit in trying to steal Brexit from the true believers. Hardened remainers, meanwhile, think that the mainstream media is working against them and lying to the public about the dangers of Brexit.

It's all a bit trippy for a country used to stability and relative normality.

We might not know the source of this leak for a long time. But short of it being the result of foreign interference -- which, though unlikely, isn't being ruled out -- then it will likely have come from someone high up in government or the civil service.

The letter will have been sent to a restricted list. As Christopher Meyer explains: "Kim has sent highly-sensitive material to a very limited audience and people have copied it who shouldn't have copied it, and it has fallen into the hands of someone who's carried out a major sabotage of his ambassadorship for political reasons."

Having diplomats unable to trust the government back in their capital city or the civil service that is supposed to support them is not healthy for any country, let alone one about to take the largest leap into the unknown in its post-war history.

"The leaking of this kind of information is more important than the drama of how a sitting president responds to a sitting ambassador. It's a deeply worrying sign of at a time of national confusion," Tom Tugendhat, who chairs the Foreign Affairs Select Committee, told CNN. "It's, at best, a bad message to be sending to the world as we leave the European Union -- and at worst, a kind of treachery."

Ever since the Brexit vote, the UK has often appeared unaware that people outside are watching. That applies to the Europeans, whom any kind of post-Brexit deal will need to be negotiated with. It also applies to the US, a nation that Brexiteers often single out as the UK's best ally after Brexit.

The reality is that the more unstable an impression the UK gives, the harder any of this will be. It doesn't matter how much Trump claims to like Brexit, or the EU claims to want a good deal. If Britain continues to look unreliable, it may find it has fewer friends on the global stage it wanted to stand on after Brexit.