1) The OP to which you responded is confusing peacefulness with being civilised. Japanese are not particularly peaceful, but they are highly civilized. Much more so than western countries (in particular the USA seems to have rather low standards in terms of politeness and civilization), because the Japanese culture places much more value on such things than the various western countries.

2) You are conflating the disposition of the foreign policy of a country with the cultural accepted practices by the population of that country.