With four months to go until it hosts the Apec Economic Leaders’ Meeting, the southern Chinese city of Shenzhen is already tightening its security, banning travellers on the subway from carrying perfume and imposing a no-fly zone for drones. In a notice on Sunday, the city government said that subway passengers would be scanned and their carry-on items would be X-rayed to “completely ensure travel safety”. In addition to items such as explosives that have long been banned on the system,...