If by WMDs you mean nuclear weapons, it's quite instructive to contemplate why:

India and Pakistan have never used them against each other

Thatcher never used them against Argentina

Israel has never used them against its surrounding "enemies"

The US has never used them in Vietnam or Central America

Russia has never used them against Afghanistan or Ukraine

They were never used by anyone in all the decades of the Cold War.

A good starting point would be to consider the world's recoil in disgust from the two bombs dropped on Japanese civilians. After that, you can talk about deterrence, though the main element of that to me would be that the nuclear game would not be worth the candle, rather than the direct fear of the shock and awe. Any leader inclined to indulge would be in mortal risk of destroying his own country as well as himself and his regime.