IT would have ben impossible to believe a few years ago, but there is no doubt that this week's visit to the US by Hu Jintao, China's president, marks a meeting of the world's two greatest powers. Japan's economy may still be bigger -- just -- and Russia's military might greater -- just -- but, taken altogether, China is Number Two.
Because of its size and population, it hopes and plans to be Number One someday. How it goes about that, and how the US responds, will be the great geo-political question of the next decades, on which both peace and prosperity will depend
The last two years have not been encouraging, with disputes over China's huge trade surpluses, its attitude to Taiwan and North Korea, and fears about its military build-up and mopping up of strategic assets, especially in Africa.
The rise of Germany and Japan around the turn of the 20th century sparked tensions, protectionism and, eventually, war. There is more mutual economic dependence between the new Big Two, and full-scale war is unthinkable, but such an enormous transition will not be easy to manage.
No meeting can put an end to such rivalries, but perhaps this one will halt the recent slide in relations.
Unlike some other occasions, Mr Hu has made conciliatory noises in advance, and even a seasoned Chinese politician may not be entirely immune to the Obama charm.