North Korea yesterday claimed it had tested an underwater nuclear attack drone able to unleash a "radioactive tsunami", as it blamed recent US-South Korea exercises for a deteriorating regional security situation. Pyongyang carried out military drills of its own in response this week, the official Korean Central News Agency said, including test-firing a new nuclear-capable underwater drone. The weapon's mission is to "stealthily infiltrate into operational waters and make a super-scale radioactive tsunami ... to destroy naval striker groups and major operational ports of the enemy," it said. The new weapon, called Haeil, "can be deployed at any coast and port or towed by a surface ship for operation," the report said.