By Gordon Corera Security correspondent, BBC News
The deputy director of the US National Security Agency (NSA), Richard Ledgett, has warned of the increasing danger of destructive cyber attacks by states.
He told the BBC: “If you are connected to the internet, you are vulnerable to determined nation-state attackers.”
He said nations would need to identify red lines that should not be crossed.
He also said agency targets, numbered in “the high hundreds”, had discussed leaks by contractor Edward Snowden, with some changing their behaviour.