South Korea, for a nation with only a 'truce' in a war since the 1950's, has certainly attempted the diplomatic method to resolve the war.  When your bellicose neighbor insists on developing nuclear weapons and neither China or the US can (or chooses to)  do anything about it, perhaps this re-evaluation is necessary.    I'm quite certain that the possession of nuclear weapons by Israel, for example, has made their Arab and Iranian neighbors a little more circumspect in their conduct.