Cross-border disasters along China’s frontiers are putting Beijing’s neighbourhood diplomacy to the test as climate shocks grow and expose strategic vulnerabilities. The stakes were highlighted last week after a sudden glacial collapse in the Himalayas unleashed a torrent of mud and flooding that ravaged nearby villages and the Gyirong Port between China and Nepal, leaving more than 1,250 dead in Nepal and 21 dead in the Tibet autonomous region. Thousands also remain missing. Beyond the...