Donald Trump will arrive in China exasperated that he has achieved none of his war aims in Iran – something President Xi will use to his advantage, writes world affairs editor Sam Kiley

Iran war, tariff setbacks and sliding US poll numbers reshape the balance going into next week’s high-stakes talks.

The US president will be counting on China to influence Iran and help him out of his latest mess. But the price may be high – including for Taiwan, says Guardian foreign affairs…