I would say the "blame" is transferable indefinitely. The reactor is not responsible either, the enriched uranium is responsible instead, for the damage. But then uranium is not responsible either, the atoms are, that fuse (or fission), or the momentum (of atoms) can also be at blame. There has to be a line that needs to be drawn here.

Wrench can explode a reactor, but it is not made specifically to blow up a reactor. Stuxnet, on the other hand was specifically made to do the damage to fuel cells. Hence it's a weapon and wrench is not.

A wrench is a weapon in the war against loose bolts. However, most people would probably call it a weapon only when wielded with the intention of hitting another person.

I don't think it's fair to characterize the intention of stuxnet as blowing up reactors. From what I've read, the purposeful damage it was designed to inflict was to disable uranium-enriching equipment. I don't recall reading anything about purposeful attempts to use the software to kill or wound.

That's where I'd draw the line: purposeful killing. So I'd describe this as a case of cyber-sabatoge -- not a case of cyber-war.

Here's an attempt at an outline of an argument that Stuxnet was used to kill or wound. Note that I don't necessarily hold this as my belief.

1. Stuxnet was designed to slow Iran's progress toward developing their own nuclear power (and weapons).

2. Nuclear power is a cleaner alternative to burning fossil fuels.

3. Fossil fuels are the cause of many deaths through pollution, mining accidents, and wars over oilfields.

4. Therefore, by delaying Iran's use of nuclear power, Stuxnet resulted in an increase in killing or wounding, via wars over oil and pollution.

That's where I'd draw the line: purposeful killing. So I'd describe this as a case of cyber-sabatoge -- not a case of cyber-war.

Sabotage can be a tactic used in an ongoing war.

Read Richard Clarke's _Cyberwarfare_. There are some tech errata, but it's still a good introduction to the subject.