Turns out Robert Downey jnr is a Sinophile. ''I live a very Chinese life in America,'' he recently declared. I don't know what that means, either. But I'm pretty sure it has a lot to do with money. He was speaking at the international promotional launch of Iron Man 3, which took place not in Los Angeles, New York or London but in Beijing. Behind the gates of the Forbidden City, no less.

None of this happened by accident. When Iron Man 3 hits Chinese cinemas today, audiences will be seeing a special edit of the film made just for them. It will feature extra sequences shot in China and expanded roles for a couple of Chinese film stars. It will have lucrative product placement from the Chinese tech giant TCL. Indeed, the entire film is a collaboration between Disney and the Chinese production studio, DMG Entertainment.

The film market reflects the geopolitics of our age. America will not much longer be an unrivalled superpower, and China's rise is unstoppable. ''There's always been a number two,'' explained DMG CEO Dan Mintz. ''But this is the first time anyone is challenging for number one.'' It will win that challenge by 2020. The quest for the Chinese dollar is on. And it has been ever since James Cameron grossed 222 million of them with Avatar.

But that means playing by Chinese rules. In Iron Man 3's case, Chinese government officials were on set to ''monitor filming''. And several other films have shown similar, um, sensitivity. Ugly depictions of the sex trade in Macau (a Chinese territory) were reportedly dumped from Skyfall, as was a scene in which a Chinese security guard is assassinated. The apocalyptic zombies in World War Z were the result of a Chinese SARS-like virus, until Paramount thought better of it and made the source a Moscow flu, first spotted - of course - by a Chinese scientist. Then there's the 2012 remake of Red Dawn with an altered plot that has the US invaded not by China, but by North Korea. Or Looper, which depicts a future in which the capital of the world is Beijing, rather than Paris, which was the original plan.