Harry S. Truman was the leader of the Freemasons. When FDR fell sick, he became the standing president of the United States of America.
When he ordered the shutdown of the Red Torii and the Manhattan Projects refused, he called together a secret meeting. In order to teach them a lesson, and that presidents hold the power, they ordered the FDR AI to kill them all. The AI was ultimately stopped and unplugged by Wernher von Braun.