This chapter describes an International law is enforced by the process as reciprocal-entitlement violation. It shows reciprocal-entitlement violation is a mechanism akin to the old "just war" notion that underlies a realistic enforcement mechanism or international law. Under the McDougal-type argument, international communication itself is "law" irrespective of its being couched in legal terms. Taken together, both of these positions may convince the reader that international law is really law. Some early writers on the law of nations attempted to meet the enforcement objection head-on, by asserting that rules of international law are indeed enforced by the mechanism of war. There is a danger in relying on the enforcement of international law by allowing a retaliatory deprivation of the offending nation's entitlement. International law is a very realistic component of the picture that political scientists try to draw of how nations behave.