On Wednesday morning, Beijingers living near Tiananmen Square were issued with cold breakfast packs and ordered to refrain from cooking, lest smoke from stoves cloud the skies above the mammoth military parade. Mr Xi embraced Mr Kim after Mr Trump wooed the North Korean leader. But it is decades since the People’s Liberation Army saw action and a widening purge, including of generals promoted by Mr Xi himself, suggests he is still concerned about its corruption, political reliability or both. Mr Trump is surrounded by China hawks. Yet the biggest imminent threat to Taiwan is probably not that Chinese military confidence leads Mr Xi to risk war with the US, but that Mr Trump rats it out for a trade deal.