1968: Besides the thousands of tons of bombs dropped from B-52 Stratofortresses on the Ho Chi Minh Trail (or the Truong Sơn trail, as it was known in Vietnam) to interrupt the movement of North Vietnamese personnel and supplies, the Americans turned to electronic gadgetry (“beep and bang” warfare) and a range of specially designed ordnance.
Toxic defoliants were sprayed on jungle vegetation. Aspirin-sized bombs were intended to burst tyres and to maim foot soldiers. A chemical agent was used to turn soil into grease. There was even a scheme to drop Budweiser beer (of which the North Vietnamese were supposedly very fond) so that drunkenness would impede their movements.
Source: Christopher Robbins, The Ravens: Pilots of the Secret War in Laos (1988), pp. 290–1