[flukus]

In Wargames they detected a massive preemptive attack. One of the things that tipped off the officer in this case was that it was such a small scale attack, which doesn't make sense because it leaves the enemy willing and able to respond.

[_coldfire]

From the article:

Taught that in case of a real attack the US would have gone on an all-out offensive, Petrov told his bosses the alarm must have been caused by a system malfunction.