Beijing on Sunday told Chinese companies that deal with critical information to stop purchasing products from Micron Technology, the US-based manufacturer of memory chips used in phones, computers and other electronics. Many analysts viewed the move as retaliation for Washington’s efforts to cut off China’s access to high-end chips. In a statement on its official social media site, the Cyberspace Administration of China said that in a cybersecurity review it had found that the chipmaker’s products posed “relatively serious cybersecurity problems”. The problems could “seriously endanger the supply chain of China’s critical information infrastructure” and threaten national security, it said....