American whistle-blower Edward Snowden said Beijing’s use of technology to control its citizens and electronically track US targets prompted him to investigate and then expose Washington’s mass surveillance programme. In his book "Permanent Record," published on Wednesday, the former US spy agency contractor who now lives in exile in Russia, detailed how he fled to Hong Kong and then Moscow after creating one of the most serious security breaches in American history. Snowden, who was a technician subcontracted to the National Security Agency and the Central Intelligence Agency for seven years, said he began to have suspicions about secret post-September...