Spooky! Whodunit?

I have always felt that cyberterrorism is an under-examined question.
But how about cyber warfare conducted by a nation state? Richard Clarke didn't say anything about that.

Stuxnet is essentially a precision, military-grade cyber missile deployed early last year to seek out and destroy one real-world target of high importance – a target still unknown.

And...

A geographical distribution of computers hit by Stuxnet, which Microsoft produced in July, found Iran to be the apparent epicenter of the Stuxnet infections. That suggests that any enemy of Iran with advanced cyber war capability might be involved, Langner says. The US is acknowledged to have that ability, and Israel is also reported to have a formidable offensive cyber-war-fighting capability.

Could Stuxnet's target be Iran's Bushehr nuclear power plant, a facility much of the world condemns as a nuclear weapons threat?