This book offers a unique and insightful econometric evaluation of the policies used to fight transnational terrorism between 1990 and 2014 using a sample of 124 countries. It proves that foreign aid plays a crucial role by inducing recipient governments to protect the donors' political and economic interests within their sphere of influence. In contrast, US troops on the ground are counter-productive as they increase the supply of terrorist attacks from the host countries, even though this effect has been significantly reduced by the Obama administration.