Frank Bajak, The Associated Press BOSTON (AP) – State-backed Chinese hackers have been targeting U.S. critical infrastructure and could be laying the technical groundwork for the potential disruption of critical communications between the U.S. and Asia during future crises, Microsoft said Wednesday. The targets include sites in Guam, where the U.S. has a major military presence, the company said. Hostile activity in cyberspace – from espionage to the advanced positioning of malware for potential future attacks – has become a hallmark of modern geopolitical rivalry. Microsoft said in a blog post that the state-sponsored group of hackers, which it calls…