President Donald Trump laudably committed to making the US more secure, to better protecting the country against physical, economic and other threats which could be transmitted to it from Mexico.

In the 23 years I have worked in the defense sector, a fundamental and almost universal lesson is that security depends on cooperation, more than on any physical asset. Without the cooperation of the population, not even the most precise sensors and lethal arms can defeat an insurgency. Without interagency and international cooperation, actions against transnational criminal organisations only displace the threat. Read more