San Francisco

US President Barack Obama's newly installed Defense Secretary Ash Carter toured Silicon Valley last week to announce a new military strategy for computer conflict, starting the latest Pentagon effort to invest in promising startups and to meet engineers whose talent he declared the Pentagon desperately needed in fending off the nation's adversaries.

He immediately acknowledged, though, the need to rebuild trust with Silicon Valley, whose mainstays - like Apple, Google and Facebook (whose new headquarters were toured by Mr Carter) have spent two years demonstrating to customers around the world that they are rolling out encryption technologies to defeat surveillance. That, of course, includes blocking the National Security Agency, a critical member of the military-intelligence community.