The Quebrada del Yuro, deep in the stifling Bolivian jungle 75 miles north of Camiri, is a steep and narrow ravine that is covered with dense foliage. There, early last week, two companies of Bolivian Rangers totaling more than 180 men split into two columns and quietly stalked a handful of guerrillas. Shortly after noon, the troops spotted their men, and both sides opened up with their rifles and automatic weapons at a withering, point-blank range of 150 feet. After a lengthy fight, four Rangers and three guerrillas lay dead, and four other guerrillas had been captured.
One of the...