Xi vs Biden at the UN; the Quad meets; ASEAN AUKUS anxieties; China's nuclear policy reconsidered?

The SCMP’s Washington bureau chief Rob Delaney analyses speeches from Presidents Xi Jinping and Joe Biden at the UN General Assembly, and calls for the Quad to expand membership; Beijing-based reporter Laura Zhou on an ex-diplomat's calls for China to change its policy regarding nuclear weapons and missile proliferation, including its first-strike nuclear strategy towards the US, and the University of Tasmania’s James Chin explores Southeast Asian tension and Asean affairs.