Part 1-Was the dropping of the atomic bombs on Japan justified? Why or why not?

Part II-The Democratic People's Republic of Korea (DPRK called North Korea) has nuclear weapons and cites the United States' nuclear weapons as a threat. Iran has discussed possessing nuclear weapons and cites Israel's possession of nuclear weapons as a threat. Do you think these nations are justified in having nuclear weapons or wanting to possess them given that other nations around them possess nuclear weapons? Should all the nuclear weapon states give up their nuclear weapons for the sake of world peace?