This July will mark the 4th annual Transatlantic Workshop bringing together academic, military, and government experts to discuss current challenges in international humanitarian law. Over the course of two days, participants will exchange views on specific challenges in relation to the interpretation and application of IHL to the conduct of hostilities, and a number of procedural obligations in the law of armed conflict. The workshop will be divided into six topics, each of which has been allocated a full session (either morning or afternoon).  We begin on the first day with a discussion on the targeting of war sustaining activities and then move on to consider the principle of proportionality, and finally the procedural regulation of detention. On day two, participants will be invited to examine, the obligation to investigate IHL violations, fair trial guarantees in armed conflict, and the role and utilization of legal advisers. Over the course of the workshop, discussions will centre on issues that have arisen in practice in a number of recent conflicts, as well an examination and comparison of the position taken by the various states involved.