Artillery equally as terrifying is far more efficient. The effect of gas: it contaminated the uniforms and left skin conditions which were hard to treat. Gas lingers on in trenches. The same will go for nuclear weapons, contaminated soil will be thrown into the air and will rain back on the earth. Imagine you win a battle after chemical and nuclear strikes. Your troops will be confined in their positive pressurized environments. Outside the conditions are toxic, conventional weapons maybe far more efficient to achieve your aims. I think NATO will retaliate against tactical nuclear warfare with overwhelming conventional means on the launching sites inside Russia. If putin goes one step further, there will be no winners Russia will vaporize the West will suffer horrific losses but will prevail in the long term.