BEIJING - China’s cyber-security watchdog said on Sunday that US chipmaker Micron had failed a national security probe and told “operators of critical information infrastructure” to stop purchasing its products. The probe was the latest escalation in the ongoing chip war between the United States and China, with Washington looking to cut off Beijing’s access to the most advanced semiconductors. It also came as China tightened the enforcement of its national security and anti-espionage laws. Micron’s products “have relatively serious potential network security issues, which pose a major security risk to China’s critical information infrastructure supply chain and affect China’s...