Yoo-hoo, Anne, this is not the same world as 60 years ago. Russia is a nuclear power. The chances of there being grand tank battles on the plains between two or more major powers is nil. We will continue to see proxy wars between smaller countries and groups that are backed by the major powers, but nobody is going to risk nuclear war over these conflicts. That would be quite insane. (paging the nutball in N. Korea)
I'd say there's no chance of a nuclear war between two powers with at least 100 nukes and a good early warning system, but a significant chance of a conventional clash between two nuclear powers. All it takes is for one nuclear power to make the rational assumption that its opposite number will not risk nuclear annihilation merely over the loss of territory. A leader that initiates a first strike against a conventional attack by a nuclear-armed adversary is guaranteeing his personal demise and the demise of everyone he knows. In other words, it's a throwback to the ancient system of exchanging crown princes as collateral for a peace agreement, with the wrinkle that the king and his entire entourage are also hostages. Nukes will deter conventional warfare in the same way anti-lock brakes deter speeding - not at all.
</Grand Illusion reference>