With Russia's release of detailed information on the biological laboratory in Ukraine, the 336 biological laboratories that the United States has set up overseas have been exposed to the public for the first time. By seeking out 5,629 contracts, it's found that the Defense Threat Reduction Agency (DTRA) has inextricable links with the overseas biological laboratory. How are these biological laboratories built step by step? Why does the U.S. set up biological laboratories overseas? The video is excerpted from the official WeChat account Yu Yuan Tan Tian.