The thing about war is it's always, universally and without exception to my knowledge, a product of the power elite manipulating a population into believing that another population is worthy of hatred and a threat to their safety and freedom. Sometimes war may be a matter of genuine self-defense against an aggressor, but in every one of those cases, it's because the aggressor population has been manipulated. The army that exists to defend against that aggressor will be made to serve unjust aggression against someone else later.
Case: WW2 had many populations acting in self-defense against a clear aggressor. The U.S. built up their military might to combat that aggressor. The Axis were a product of a population whipped up into a frenzy of hatred by leaders who took advantage of a period of emotional vulnerability. What did the U.S. do after the Axis were defeated? The exact same fucking thing. Their leaders whipped up their population into a frenzy of fear and hatred against first communism, and then terrorism. That military which was formed once for defense has for decades since maintained its existence as an aggressor.
And this will continue until we give up justifying the build-up of personnel and tools of war for any reason. War is a product of self-fulfilling prophecies. Two sides fighting against each other because each is convinced that they're under attack and the other's lives are worth less than their own anyway... and only one side can ever be right in this, if any at all.
No soldiers - no war. If people throw their own lives away by choice, then not much can be done about it. That's a cultural issue. Gullibility. When people are forced into it, that's something else.