Learning To Eat Soup With A Knife by John A. Nagl, Peter J. (FWD) Schoomaker (2005, Paperback)

This book is a brilliant, concise summary of over 60 years of counterinsurgency theory.

It is specifically applicable to the US Military. It explains the US Military culture, which is without a doubt the most successful modern army in the last century. Nonetheless, this remarkable success at conventional war has led to it having an institutional culture that tends to underestimate the importance of counterinsurgency warfare, and tends to adapt poorly to it, as evidenced in the Viet Nam war. Despite small successful counterinsurgency programs, the US Military never adopted an overall counterinsurgency (COIN) doctrine.

It contrasts this failure with the success of the Malaya Emergency COIN. The Birtish at first were very unsuccessful when they took a conventional approach of being there to simply find and destroy the enemy. They reassessed their situation after several years of failure, and developed a more robust COIN strategy of providing security and of changing the loyalties of the population. In the end, COIN is much about politics as it is about bullets.