This principle of the interplay between conventional and nuclear forces is fundamental to deterrence in the nuclear era. The dangerous example today of the consequences of failure to maintain strong conventional forces is Russia. Given the decline in their conventional arms, the Russians are embarked on a major nuclear buildup and leaders have starkly stated that they plan to use those nuclear forces if faced with a security threat, even if that threat is not nuclear.
Perry, William. My Journey at the Nuclear Brink. Stanford Security Studies. 2015. p. 81 (paperback)