The book Understanding Post 9/11 Cross-Border Terrorism In South Asia, U.S. And Other Nation?s Perceptions seeks to understand the causes of cross-border terrorism in South Asia in the post 9/11 period. It analyses how each South Asian Country has responded to terrorism in general and cross-border terrorism specifically. Role of each country has been analysed. This book studies the causes of terrorism and cross?border terrorism, organisations involved, countries involved, particularly on cross-border terrorism in South Asia. This book has analysed the role of United States and other big powers in countering terrorism in South Asia. It has two sections. First section deals on cross-border terrorism in South Asia. The second one deals with each South Asian country?s role in cross-border terrorism.