The original ARPANET was a proof of concept of a network which could withstand the failure multiple simultaneous nodes, that is, survive a nuclear strike. Whether knowing you have a robust command and control network makes you more or less likely to use your own nuclear weapons in a first strike is arguable. But it did guarantee a second strike would be possible (which if you believe MAD, made the world safer.) And robust second-strike capability, in the end, is about killing people.
