Every country does not have a right to defend itself how they see fit. They do have a right to defend themselves, but there are rules that must be followed.
For example, the use of nuclear warheads just being used at the slightest provocation. They aren't supposed to be using chemical warfare either, there are rules of war. There are many rules of warfare that people are supposed to be abiding by, see the Geneva Convention. If they don't follow the rules, they are tried for war crimes & then they get the whole of the UN on them.
A country can not destroy the planet just because they see fit. That is why North Korea can't have nuclear technology or Iran, etc... Not trusted to not use nukes. The whole weapons of mass destruction ordeal.