ABCD line

The ABCD line (ABCDライン) was a Japanese name for a series of embargoes against Japan by Western nations, including America, Britain, China, and the Dutch. It was also known as the ABCD encirclement (ABCD包囲陣). In 1940, in an effort to discourage Japanese militarism, these Western powers and others stopped selling iron ore, steel and oil to Japan, denying it the raw materials needed to continue its activities in China and French Indochina. In Japan, the government and nationalists viewed these embargoes as acts of aggression; imported oil made up about 80% of domestic consumption, without which Japan's economy, let alone its military, would grind to a halt. The Japanese media, influenced by military propagandists, began to refer to the embargoes as the "ABCD ("American-British-Chinese-Dutch") encirclement" or "ABCD line".

Faced with a choice between economic collapse and withdrawal from its recent conquests (with its attendant loss of face), the Japanese Imperial General Headquarters began planning for a war with the Western powers in April or May 1941.