Cyberwars?

The recent issue of http://technews.acm.org/ quotes an article of Bruce
Schneier in Financial Times entitled "It Will Soon be Too Late to Stop
the Cyberwars" as follows:

Schneier suggests setting up a hotline between the world's
cybercommands, so that communication between governments can
hopefully produce more constructive results than bare speculation.
There also should be established new cyberwar pacts that could
stipulate a no-first-use policy, declare unaimed weapons unlawful,
or authorize the use of weapons that destroy themselves at the
conclusion of hostilities.

But does cyberwarfare necessarily need to be initiated from the
government of a country? Wouldn't it be conceivable that even a single
hacker might acquire knowledge of the needed software techniques to
cause damage of that scale? If yes, what could be the use of such
topics as "no-first-use policy", etc.? Further, the existence of
weapons, including ABC, could be physically proved, but the existence
of weapons for cyberwars is IMHO barely provable, for these may be only
bits residing on, say, an USB stick. So how is any international arms
control going to look like in respect of cyberwars?

M. K. Shen