Since the 2003 U.S. led invasion of Iraq, the private military sector has seen the largest growth of profit for decades. As Iraq continues to be the focal point of private military clients, staff and related actors, the recurring issue of legitimacy must be addressed. While many texts focus only on existing or proposed legislation, this book analyses the public perception of private military companies (PMCs) and, of wider significance, how their use by states affects how the general public perceives state legitimacy of monopolizing force. Furthermore, this book provides a timely overview of how the energy sector and PMCs are challenging the established sovereignty of politically fragmented oil states, illustrating how energy firms may become as culpable as states in their partnerships with the private military sector and subsequent political ramifications. 'Due-Gundersen's book takes a more innovative approach than the existing literature which predominantly addresses the legal status of PMCs, positioning itself in the broader debate on the state's monopoly on the legal use of force. It may be a relatively complex read for beginners, but surely provides interesting food for thought for International Relations scholars and academics. 'Mihaela Luchian in The International Spectator (2018) 153