The relentless modernisation of weaponry, the transformation of military strategy, and recent conflicts incorporating both these trends, especially in response to the War on Terror (WOT), raise two questions with regard to jus in bello: does the almost exponential increase in the use of modern weaponry and commensurate changes in military strategies foster compliance with jus in bello or, alternatively, does it make its observance less likely. Second, is jus in bello in danger of becoming increasingly irrelevant in the era of post-modern asymmetrical warfare. If so, can jus in bello be adapted to meet these new challenges? Answering these two questions, this article describes jus in bello, reviews how advances in weapon technology and force structure have been reflected in recent military operations, and identifies key jus in bello issues that have arisen in these recent conflicts. The article also surveys how technology and jus in bello impacted changes in US military strategy and future weapon modernisation efforts, and concludes by noting that weapon modernisation and new military strategies have proceeded within jus in bello and have fostered its observance ensuring that jus in bello will survive the unique challenges posed by non-conforming terrorists and belligerent states.