The ABCD line (ABCDライン, Ēbīshīdī rain) was a Japanese name for a series of embargoes against Japan by foreign nations, including America, Britain, China, and the Dutch. It was also known as the ABCD encirclement (ABCD包囲陣, Ēbīshīdī hōijin). 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 the possibility of economic collapse and forced withdrawal from its recent conquests, the Japanese Imperial General Headquarters began planning for a war with the Western powers in April 1941.