We still do have those real wild adversaries. Russia and China are only two that are of the conventional type.

The less obvious ones are the ones we don’t think about so much. Iran, Iraq, North Korea, India, Pakistan, Argentinian at one time and so fourth. Most of these countries stay in line predominately because they now understand the likelihood of Western nation military involvement it they act too aggressive.

Point being if all Western nations backed out of the arms race right from the beginning. From WW2, I suspect WW3 would have happened long ago. One or more of those other countries would be far more active in one way or another. If we backed out now, it also would not be long run those same countries realize they could act without impunity. Nothing has really changed. Just the military damage potential is far more serious.