  The possibility that extraterrestrial intelligences (ETIs) could be hostile
to humanity has been raised as a reason to avoid even trying to contact ETIs.
However, there is a distinct shortage of analytical discussion about the risks
of an attack, perhaps because of an implicit premise that we cannot analyze the
decision making of an alien civilization. This paper argues that we can draw
some inferences from the history of the Cold War and nuclear deterrence in
order to show that at least some attack scenarios are likely to be exaggerated.
In particular, it would seem to be unlikely that the humanity would be attacked
simply because it might, some time in the future, present a threat to the ETI.
Even if communication proves to be difficult, rational decision-makers should
avoid unprovoked attacks, because their success would be very difficult to
assure. In general, it seems believable that interstellar conflicts between
civilizations would remain rare. The findings advise caution for proposed
interstellar missions, however, as starfaring capability itself might be seen
as a threat. On the other hand, attempting to contact ETIs seems to be a
relatively low-risk strategy: paranoid ETIs must also consider the possibility
that the messages are a deception designed to lure out hostile civilizations
and preemptively destroy them.
