In 1965 Evernden, a Berkeley-trained seismologist, became involved in the scientific-technical-political debate about the seismic detectin of underground nuclear weapons tests. From 1965 to 1969 Evernden worked inside the Department of Defense as a sesimologist expert, first for the secret Air Force Technical Applications Center, later for the Advanced Research Projects Agency. He soon became convinced that only a few seismologists were actively working towards a solution of the detection problem, and that a number of individuals tried to prevent such as solution to the test ban treaty issue. Since then he has been an outspoken supporter of a Comprehensive Test Ban Treaty and critic of the Department of Defense's work on seismic detection.