18 January 2013 Last updated at 05:16 ET

US general warns over Iranian cyber-soldiers

Iran's nuclear programme has been hit by viruses that targeted industrial machinery

Cyber-attacks on Iran are turning it into a "force to be reckoned with" America's top cyber-soldier has warned.

Since 2010, Iran has come under attack many times by malicious viruses written specifically to target key industrial installations in the country.

The repeated attacks have provoked Iran to improve its cyber-capabilities, said Gen William Shelton who oversees US cyber-operations.

It meant Iran was becoming a growing force in web-based attacks, he said.

Gen Shelton issued the warning during a briefing given to reporters about the US Air Force division he heads that includes America's cyber-troops.

He said the 2010 Stuxnet virus attack on Iran's Natanz uranium processing plant had generated a "reaction" by Iran that had led it to rapidly improve its defensive and offensive cyber-capabilities. Since then Iran has been hit again and again by viruses. In December 2012, the Stuxnet virus returned and hit companies in the southern Hormozgan region.

That improved capability had helped it protect itself against subsequent attacks on oil terminals and other manufacturing plants. Its capability might well be turned against Iran's enemies in the coming years, he said.

"They are going to be a force to be reckoned with," said Gen Shelton, "with the potential capabilities that they will develop over the years and the potential threat that will represent to the United States."

Web war

Gen Shelton's comments come soon after a senior Iranian commander said it had growing "electronic warfare" capabilities that it planned to use to disrupt what it called enemy communication systems. The nation is known to have carried out web-based military exercises at the same time as other troops were on manoeuvres.

Currently, said Gen Shelton US cyber-forces were about 6,000 strong but would add another 1,000 people in the next 12 months. These workers were successfully fending off the vast majority of the millions of attacks aimed at military networks every day, he added.

In addition, he said, the cyber-forces could gather intelligence and were developing the ability to carry out hack attacks in support of more traditional military operations.