SEOUL, Aug. 12 (UPI) -- North Korea conducted artillery firing drills to boost combat readiness, state-run media reported Tuesday, as the United States and South Korea prepare to kick off a large-scale joint military exercise. A firing practice contest of tactical artillery sub-units was held on Monday under a "combat drill plan of the [Korean People's Army] General Staff for perfecting the capability to fight a war and battle readiness of the entire army," the official Korean Central News