The Chinese and North Korean governments are thought to be responsible for some cyber hacking of western companies and governments.
Some IT experts say the hackers who breached Sony's computer network late last year and leaked huge amounts of confidential information were backed by the North Korean state.
Pyongyang has consistently denied involvement in the security breach.
James Lewis, a cybersecurity expert at the Center for Strategic and International Studies in Washington DC, said that government-backed attackers have far greater resources at their disposal than criminal hacker gangs.
They may be able to use other measures such as human agents or communications intercepts to successfully bypass any security measures, he said.
