Directive on the Report of On-the-Spot Observation [I]
(October 27, 1964)

Only fortifications, low walls, strongholds, and the like can defend against nuclear explosions and prevent injury to people.

Mao Zedong
October 27

[I]
This is Mao Zedong's directive on the report of Zhang Aiping, Deputy Chief of the General Staff of the Chinese People's Liberation Army and Deputy Director of the National Defense Science and Technology Commission, and Liu Xiyao, Vice Minister of the Second Ministry of Machine Building and Deputy Director of the National Defense Science Commission, on October 26, 1964.

[2]
Zhang Aiping and Liu Xiyao's report stated: According to our observation of the effects test at the atomic bomb test site these past two days, we preliminarily believe that exposed organisms on the ground will mostly die successively within a certain distance; beyond a certain distance, although they will not die, they will lose their combat effectiveness. Various combat weapons deployed exposed on the ground will be mostly destroyed within a certain distance or unusable in a short period of time; beyond a certain distance, as long as slight protection is added (such as field shelters), there will be basically no impact. Various fortifications, shelters, especially underground fortifications, have good protective capabilities against atomic bomb explosions.

[Image caption]
October 16, 1964, China's first atomic bomb explosion test was successful.