Massive Mail Censorship Program Hid North Korea Accusations of U.S. BW, Collaboration with Unit 731 War Criminals

Jeffrey Kaye
16 min readJan 5, 2021

Awhile back, as I was still trying to put together an understanding of the charges of use of U.S. biological weaponry during the Korean War, one well-known scholar wrote to me (bold added for emphasis), “I have spent quite a bit of time and effort investigating the various and multiple allegations of BW, CW and other atrocities brought forward by the North Koreans and Chinese during the Korean War. This includes collecting them, which is no simple matter, since most were intercepted and destroyed by US postal officials during the Korean War, and so are often absent or fragmentary in academic libraries.”

If, as the title of my essay states, during the Korean War North Korea charged that the U.S. had worked with the bacteriological criminals of Unit 731, so what? Well, the issue here isn’t merely that the North Koreans thought this, or even that the accusations were true or not. The issue is that the subject itself became censored in the West. The reasons for that are many, and we will explore some of them below.

Why can’t I read historical documents in “free” America?

The simple answer to this question is that the documents aren’t available. But the reasons they aren’t available vary. When it comes to documents from the period of the Korean War, most Americans are totally unaware that during the 1950s and first half of the 1960s, the U.S. government “engaged in wholesale confiscation of publications mailed into this country” from Communist countries. This meant any materials emanating from North Korea, China, the Soviet Union or other allied countries (such as those in East Europe at that time) were intercepted and destroyed by U.S. postal officials.

Screenshot from article in Univ. of Penn Law Review, Vol. 107 (1959)

As a result, even academic libraries and archives, which otherwise might have been the repository of such documents, didn’t carry copies of such materials. Only a small handful of such archives, such as the Hoover Institute, or the Library of Congress, might carry such records.

The confiscation of this material — which included items as innocuous as chess manuals and mathematics texts — stemmed from an executive branch interpretation of the 1938 Foreign Agents Registration Act (FARA) law…