Iran and others suspect Israel was behind the so-called Stuxnet computer worm that hit the Islamic Republic's Bushehr nuclear plant and industrial targets in early September.

The perpetrators may never be identified. But with little fanfare Israel, through Unit 8200 of Military Intelligence, has become a world leader in cyberwarfare, and is also desperate to cripple Iran's nuclear program.

The United States, whose high-tech, heavily automated economic and security sectors are highly vulnerable to cyberattack, has also been devoting much time and treasure to develop a cyberwar capability.

Both are also thought to be conducting covert operations aimed at disrupting the Iran's nuclear project, including luring scientists into defecting or assassinating them.

Israel, which due to its geographical proximity to Iran views a nuclear-armed Tehran regime as an existential threat, arguably has a greater incentive to do so.

The Iranians, obviously, are extremely tight-lipped about their nuclear program. But word has leaked out of mysterious explosions and technical failures that appear to have set back the program.

One explanation for these events has been that U.S. intelligence services had penetrated Tehran's clandestine network that procures components for the nuclear program that resulted in Iran receiving sabotaged equipment that broke down.

However, the Stuxnet epidemic now suggests these may have been result of cyberattacks.

Iran has said some 45,000 industrial units were struck by the Stuxnet malware in September, although Western information technology experts suspect the scale of the disruption in Iran was far greater. It's not clear whether Iranian military command centers were affected.

Iran's recent nuclear reverses apparently have centered largely on its ability to enrich uranium, a vital process that produces weapons grade material.

In May 2009, the International Atomic Energy Agency, the U.N. nuclear watchdog, reported that Iran had 4,920 operational centrifuges to enrich the uranium. A year later, the agency said the number had fallen to 3,936, a 20 percent drop.

A month after the Stuxnet attack became known, Iran's intelligence minister, Haydar Moslehi, said Oct. 3 authorities had arrested several "spies" involved in efforts to sabotage the nuclear program.

The Iranian government had sought to downplay the significance of the cyberattack but the reported arrests indicate the regime was more alarmed than it cared to admit.

In the aftermath of the Stuxnet rampage, there have been unconfirmed reports in Israel that Iran's computer experts haven't been able to defeat the worm.

According to these reports, Tehran has been secretly contacting computer security specialists in Western and Eastern Europe with offers of hefty fees to exorcise the worm from Iran's systems.

If that's true, then Tehran should expect further cyberattacks and should be greatly concerned that its ballistic missile program could be targeted as well, along with its military command-and-control centers.

"Creating such a program, which targets a specific Siemens software system controlling automated activity in large industrial facilities, would have required a large team with experience and actionable intelligence," says the U.S. global security consultancy Stratfor.

"If a national intelligence agency in fact targeted Iranian nuclear facilities, this would mean the first deployment of a cyberweapon reported on in the media."

Israel's highly secret cyberwar program is run by Unit 8200. It has a strength of several thousand soldiers, making it Israel's largest army unit.

It compares with the U.S. National Security Agency, which conducts global electronic surveillance and is arguably the most sensitive agency in the Western intelligence establishment.

Unit 8200's main center is hidden deep in the Negev Desert in southern Israel near the biblical city of Beersheba. Its work in developing cyberwar capabilities is shrouded in secrecy.

But no less a figure than the chief of Military Intelligence, Maj. Gen. Amos Yadlin, noted at a Tel Aviv symposium in February that Israel is becoming a world leader in cyberwarfare.

It was the first time this issue had been discussed in public and perhaps indicated Israel had something up its sleeve. Yadlin declared enthusiastically, "Cyberspace grants small countries and individuals a power that was heretofore the preserve of great states."