South Korean troops fire to repel North soldiers' 3rd border incursion. Activists fly more leaflets

South Korea’s military says it fired warning shots for the third time this month to repel North Korean soldiers who temporarily crossed the rivals’ land border. The announcement Friday came as an activists’ group said it flew more balloons carrying propaganda leaflets toward North Korea. That campaign has aggravated animosities between the rivals and prompted a resumption of Cold War-style psychological warfare along their border. South Korea's military has said it believes the two earlier incursions were accidental. Large numbers of North Korean soldiers are working in frontline areas to fortify their side of the border, possibly to prevent defections.