The following video is a very interesting 2010 Aljazeera documentary examining the decades-old claims that the United States used biological warfare weapons during the Korean War. The use of such weapons would constitute a significant violation of the Geneva Conventions and the laws of war. But when the Imperial Japanese Army did the same thing to China during World War II, the U.S. government helped cover up the fact and gave amnesty to the scientists and military officials involved, even though they had used hideous and criminal experiments on prisoners to perfect their use of anthrax, plague, glanders and other BW terrors.
Were Lt. General Ishii Shiro and the many Japanese scientists and doctors associated with Unit 731 and like BW and Chemical Warfare units run in Japanese-occupied Manchuria and China, not to mention other occupied areas like Burma, later used as "experts" for the US in its operational tests of BW in the Korean War? Watch the documentary and see what you think.
Unique in documentaries on the subject, Aljazeera uses copious amount of film clips from confessions by U.S. flyers held by the North Koreans, as well as their filmed retractions after their release. (Here is a link to a transcript to one of these confessions, posted by an academic online.)
More about the deal between Fort Detrick scientists, blessed by the US State Department and Departments of War and the Navy at the time, can also be viewed in this clip from a History Channel documentary.
Of additional interest, should readers have the time (consider this a double feature of sorts) is this German documentary (with English narration) on the CIA's Operation Artichoke and the murder of former Ft. Detrick scientist (and CIA agent) Frank Olson. The documentary ends up going back to the inevitable dilemma of the deal with the Ishii and his gang. It also unearths documents that show returning flyers from the Korean War who had confessed to dropping BW bombs in Korean and China were subjected to Artichoke "brainwashing" procedures after their return. I don't think I had seen that before.
If you watch all this, you may very well suffer vertiginous feelings of unreality. If you are looking for more to document what you have watched there are books and articles written by dedicated historians and academics who have nearly single-handedly kept this important aspect of U.S. history alive after the government has done what it can to bury it forever.
The United States and Biological Warfare: Secrets from the Early Cold War and Korea by Stephen Endicott and Edward Hagerman
Factories of Death: Japanese Biological Warfare, 1932-45 and the American Cover-Up by Sheldon Harris
A Terrible Mistake: The Murder of Frank Olson and the CIA's Secret Cold War Experiments by H. P. Albarelli Jr.
A Plague upon Humanity: The Hidden History of Japan's Biological Warfare Program by Daniel Barenblatt