In the annals of western intelligence blunders, the failure to notice the Sino-Soviet split in the frigid depths of the cold war looms very large. Despite a small group of heretical CIA officers pointing to mounting evidence from the late 1950s onwards, successive governments in Washington and elsewhere refused to believe that the two biggest members of the communist bloc actually hated each other. It was not until China and Russia fought a war along the Siberian-Manchurian border in 1969 that the sceptics finally accepted the schism was real.

Today the west risks making the opposite mistake by dismissing the anti-western, anti-US alliance that is now forming between Moscow and Beijing. At a conference in Singapore in June, Jim Mattis, US defence secretary, talked about a “natural non-convergence of interest” between Russia and China and his belief that both countries had more in common with America than with each other.

This idea that Russia and China can never really be friends is just as wrong and dangerous as the cold war dogma that portrayed global communism as an unshakeable monolith.