Nuclear weapons did help save Americans/NATO and the Soviets/Chinese from killing each other in a “hot war” after World War Two was over. They didn’t end the war. Japan was already preparing to surrender to the Russians and this was known to the USA. What the bomb did is cause them to surrender to the US and create a situation where the USA and USSR could not afford to go to war against each other. Instead both sides got involved in every Third World conflict that had nothing to do with them and helped kill millions of innocent people in the process.
Nuclear weapons and all WMD need to be eventually banned worldwide. Their existence is too dangerous. As for war, once one party initiates violence there is nothing the injured party can do that does not encourage further violence. If you fight a bully or you don’t fight a bully, the bully is still going to be a bully, so pacifism in the face of naked aggression is not pro-peace. Instead it is rewarding aggression.
One of the creepiest things about Donald Trump (there are many) is his use of the slogan “America First”. The “America First” movement was a movement of largely Hitler sympathizers and anti-Semites who sought to keep the USA out of World War Two. I support the doctrine of self defense of course and of avoiding conflict whenever possible, but I also strongly support the doctrine of Responsibility to Protect (R2P) that states that all nations have a responsibility to intervene by whatever peaceful means are possible to stop wanton human rights abuses such as genocide and ethnic cleansing and massacres of peaceful dissidents…and that military options such as no-fly zones and safety corridors should be instituted if diplomacy and sanctions and criticism and negotiations don’t work to stop the carnage.
We not only have the right to defend ourselves but the obligation to defend others. Fighting Hitler was the right thing to do. Removing the Taliban from power in Afghanistan should have happened sooner. It should not have required a 9/11 to realize that a gang of ultra-conservative religious fanatics should not be allowed to take over a country by force and commit horrific crimes against humanity day after day and year after year. Bill Clinton (as wrong as he could be about many things, usually when he sided with the GOP), was correct is saying that one of the worst decisions of his Presidency was not doing enough to prevent the genocide in Rwanda.