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.
- Kokushi Daijiten ja:国史大辞典 (昭和時代) ("Historical Dictionary"), 1980: "It was not an official term, but a term of incitement used by the Japanese media, under the guidance of the military, in order to stir up the Japanese people's sense of crisis..." (Cited by Christopher Barnard, 2003, Language, Ideology and Japanese History Textbooks, London & New York, Routledge Curzon, p.85.)