From 1963 to 1969 as part of Project Shipboard Hazard and Defense (SHAD), the U.S. Army performed tests which involved spraying several U.S. ships with various biological and chemical warfare agents, while thousands of U.S. military personnel were aboard the ships. The personnel were not notified of the tests, and were not given any protective clothing. Chemicals tested on the U.S. military personnel included the nerve gases VX and Sarin, toxic chemicals such as zinc cadmium sulfide and sulfur dioxide, and a variety of biological agents.