"The strong do what they can, and the weak suffer what they must" Thucydides

True, but after this led to the disasters of WW1 and WW2, there was a genuine international effort to constrain it. Of course, it was a deeply imperfect system, especially with the cold war going on, but it was still an improvement on the naked imperialism and genocide that preceded it. Unfortunately, it appears we're rapidly regressing to the former situation, except this time with atomic weapons.