Since God is the Ruler of nations no less than individuals, His law is supreme over the external relations of states as well as the internal affairs of each. The sovereignty that makes a nation independent toward other nations, does not exempt its obligations toward God; nor can any covenant, however shrewdly arranged, guarantee peace and security, if it disregard divine commands. These require that in their dealings with one another, nations shall observe justice and charity. By the former, each nation is bound to respect the existence, integrity and rights of all other nations; by the latter, it is obliged to assist other nations with those acts of beneficience and good will which can be performed without undue inconvenience itself. From these obligations a nation is not dispensed by reason of its superior civilization, its industrial activity, or its commercial enterprise; least of all by its military power.
– Cardinal Gibbons