S eeing the limits of American power exposed by its war against Iran, China has issued an unusually blunt warning that the two countries could end up in conflict over Taiwan. For a peevish and fragile US president on a visit to Beijing , this is a humiliation. It is not something Donald Trump will feel. It will be disastrous for the region where China is already engaged in another land grab. Already puffed up by hordes of flower and flag-waving children, honour guards and meetings in China’s Great Hall of the People , it is unlikely that he’d be offended by the offensive because he doesn't care about Taiwan, is irritated by past commitments to protect the island, and sees the entire region as part of China’s legitimate sphere of influence. “You're a great leader. Sometimes, people don’t like me saying it, but I say it anyway. There are those who say this may be the biggest summit ever,” said the US president.…