The usual 600-ton opium harvests were cut to 160 tons in 1978 and 240 tons in 1979.37 The natural catastrophes were accompanied by concerted efforts by the Burmese and Thai governments to eradicate poppy production, necessitated by the fact that opium remained the main source of revenue for the Shan guerrilla armies. From 1976 to 1979, the Burmese army destroyed four major heroin laboratories near the Thai border, netting impressive quantities of precursor chemicals.38
