The network, called Ghostnet, is based mainly in China. Among the computers it targeted were those of Tibet’s spiritual leader, the Dalai Lama, and Tibet’s government-in-exile in India. Scholars say the operation may have helped identify people in Tibet who talk to exiled Tibetans, putting those in Tibet at risk of reprisals from the Chinese government, which controls Tibet.

The Canadian researchers said the spying activity they found was just the tip of the iceberg.

Keith Epstein, an investigative reporter in BusinessWeek’s Washington D.C. bureau who specializes in cyber security, joins Martin Savidge to discuss Chinese cyber spying, what information is at risk and defense systems.