China is the true power in Putin and Kim's budding friendship

While he has not condemned the invasion of Ukraine, he has so far failed to provide significant military assistance to Russia. And during the meeting in May, his cautious rhetoric was in contrast to Mr Putin’s florid compliments about Mr Xi.

So far, China has also provided political cover for Mr Kim’s efforts to advance his nuclear arsenal, repeatedly blocking US-led sanctions at the United Nations.

But Mr Xi is no fan of an emboldened Kim Jong Un.

Pyongyang’s weapons tests have enabled Japan and South Korea to set aside their bitter history to ink a defence deal with the US. And when tensions rise, more US warships turn up in Pacific waters, triggering Mr Xi’s fears of an “East Asian Nato”.

Beijing’s disapproval may force Russia to reconsider selling more technology to the North Koreans. The possibility of that happening is also one of the US’ biggest concerns.

Andrei Lankov, the director of NK News, says he is sceptical: “I don’t expect Russia to provide North Korea with a large amount of military technology.”

He believes Russia “is not getting much and probably creating potential problems for the future” if it did so.

While North Korean artillery would be a shot in the arm for Mr Putin’s war effort, swapping missile tech for it would not exactly be a great deal.

And Mr Putin might realise it’s not worth irking China, which buys Russian oil and gas, and remains a crucial ally in a world that has isolated him.

Pyongyang needs China even more. It’s the only other country Mr Kim visits. Anywhere between a quarter to a half of North Korea’s oil comes from Russia, but at least 80% of its business is with China. One analyst described the China-North Korea relationship as an oil lamp that keeps burning.

In short: however much Mr Putin and Mr Kim try to appear as allies, their relationship with China is far more important than what they share.