Concern mounts over government cyber agency’s struggle to respond to hack fallout

Washington (CNN) – With Microsoft acknowledging for the first time this past week that suspected Russian hackers behind a massive government security breach also gained access to its source code, pressure is mounting on US officials and cybersecurity experts to explain how the attackers infiltrated various US computer networks, what they did once inside and the steps that are being taken to mitigate the damage.

As US officials struggle with the fallout, questions are swirling about whether the agency tasked with protecting the nation from cyberattacks is up to the job.