Following the Japanese invasion of French Indochina, the U.S. enacted an oil and steel embargo against Japan in August 1941, and China was included in the Lend-Lease Act which superseded the Sino-Soviet Non-Aggression Pact of 1937. As the Battle of Chonqing-Chengdu continued into 1941 with "Operating 102", the Japanese began preparations for "Operation Z"; the attack plan on Pearl Harbor. In the latter half of the Sino-Japanese War.