This is an article on Leo Strauss and American foreign policy of the neo-cons. According to Strauss, the purpose of foreign policy is or ought to be survival and independence, or self-preservation, and nothing else of the good city. The fundamental rightness or wrongness of political action or policy in international relations depends on the rightness or wrongness of the political regime which it supports. For the classics, justice, or what Strauss called natural right, is to be found in the best political order, or, to use his term, the best political regime.
So the foreign policy of a sensible nation is never devoted to the good of other nations, except to the extent that the good of another nation accidentally happens to promote one's own nation's existence. For the same reason, a sensible nation will not engage in imperial expansion for its own aggrandizement—though it might have to do so for its own survival.