This paper compares the reasons given by three South-east Asian states (Laos, Thailand and Vietnam) for choosing to suppress opium production. While external pressure, often from the US or United Nations (UN)/League of Nations, is the most commonly identified reason in the literature, and was experienced in each case, it was not by itself sufficient to motivate states into action. All three cases were motivated by religious or ideological opposition to drug consumption or trade, rural development, state extension and concern for increasing domestic drug consumption. Apprehension about rising drug consumption often possessed racial or chauvinistic elements. The development of export commodities, environmental protection and national security were also identified in one or two cases. The paper concludes by hypothesising that economic and/or security considerations underlie all choices to suppress illicit drug crops.