Debates about the role and relevance of international law in contemporary world have acquired new intensity in light of the U.S. coalition's decision to invade Iraq in March 2003 without a clear legal basis or even exhausting a diplomatic solution. Some have interpreted the lack of compliance in this case as proof of irrelevance of the U.N. Charter use of force paradigm. Motivated by certain debates, this paper takes a deeper look at how international law regulates the military action on the use of force operates in the broader context of international politics and in what ways it may affect political processes and outcomes in this highly sensitive area. Integrating and building on different perspectives, the first part of the paper explores the effect of using military action on Iraq. The second part then examines the role of international relations in the processes of shaping, justifying and evaluating the diplomatic solutions before using military actions. Eventually, this paper confirms that international law on regulating military action plays a significant role in contemporary international relations.