Hammond told a two-day conference in London, hosted by the U.S.-based Electric Infrastructure and Security Council, it is increasingly likely a rogue state could use an "e-bomb" to take out the country's electronic infrastructure with an electromagnetic pulse.
"One of the challenges we face, particularly at a time of limited resources, is to make the case for spending on defense and security solutions that cannot readily be seen by the public -- that cannot be shown off on the parade ground -- that could be digital, not necessarily physical," he said.
Hammond also discussed the similar threat a solar flare could pose to the world's electronic resources, The Daily Telegraph reported.
Avi Schnurr, chief executive officer of the council, said the threat posed by an electromagnetic pulse is staggering:
"Based on reports by the U.K. Parliament, the U.S. Congress, NASA, the U.S. Department of Energy and many other agencies, the infrastructures our lives and our economies depend on have become to fragile that a hostile [electromagnetic pulse] attack or a severe solar flare could damage or destroy them on continental scales, severely disrupting electricity, water supply, transportation and communication -- for months, even years."