Adopted by the United Nations Security Council on the 28th of September in 2001, resolution 1373 was one of the collective measures or actions taken to maintain international peace and security perceivably under threat by international terrorist acts committed by Violent Non-State Actors. This interdisciplinary politico-legal thesis seeks to understand how the unique United Nations Security Council Resolution 1373 affects the Security Council in practice by using a comparative perspective tracing related Security Council follow-up activity. The conclusion derives from the application of the Jus ad Bellum dimension of Just War Theory and its six moral and international legal conditions that run in parallel with the analysis of Resolution 1373 and additional related resolutions selected out of relevance. The results show that the United Nations Security Council continue to produce quasi-legislative resolutions following the mould Resolution 1373 that in overall majority fails to adequately meet and fulfil the six Jus ad Bellum conditions.