Intelligence leaders said for the first time on Tuesday that cyber attacks and cyber espionage have supplanted terrorism as the top security threat facing the United States.
That stark assessment, in an annual "worldwide threat" briefing that covered concerns as diverse as North Korea's belligerence and Syria's civil war, was reinforced in remarks by the spy chiefs before the Senate Intelligence Committee.
They expressed concern that computer technology is evolving so quickly it is hard for security experts to keep up.
"In some cases, the world is applying digital technologies faster than our ability to understand the security implications and mitigate potential risks," James Clapper, the Director of National Intelligence, told the committee.
In written testimony, Clapper softened his analysis somewhat, playing down the likelihood of catastrophic attacks on the United States in the near term - either through digital technologies, or from foreign or domestic militants employing traditional violence.