North Korean officials are warning continued military exercises between the United States and South Korea are escalating nuclear tensions to an "extreme red line." The U.S. and South Korea vowed on Tuesday to ramp up their nuclear deterrence efforts and military drills in the face of increased hostilities from North Korea. US, SOUTH KOREA VOW TO RAMP UP NUCLEAR DETERRENCE IN FACE OF NORTH KOREA AGGRESSION In a three-day trip to South Korea, Secretary of Defense Lloyd Austin said the U.S.