Seoul, Jan 19 : North Korea on Friday said it has tested an underwater nuclear weapons system under development in response to the latest maritime trilateral drills involving South Korea, the US and Japan. According to Pyongyang's official Korean Central News Agency (KCNA), North Korean Defence Ministry said the country conducted an important test of the Haeil-5-23 in the East Sea, denouncing this week's naval drills involving a US nuclear aircraft carrier as "reckless confrontation hysteria". The KCNA did not disclose details, including the weapons's specifications and the test date, reports Yonhap News Agency. "Our army's underwater nuke-based countering posture is being further rounded off, and its various maritime and underwater responsive actions will continue to deter the hostile military maneuvers of the navies of the US and its allies," a spokesman of the Ministry said in a statement carried by the KCNA. The official condemned the three nations for "seriously threatening the security" of North Korea and sternly warned of "catastrophic consequences" for their acts, the report said. South Korea, the US and Japan jointly conducted naval drills involving the USS Carl Vinson nuclear-powered aircraft carrier from Monday to Wednesday, following Pyongyang's latest launch of a hypersonic missile. Pyongyang has long denounced joint military drills between Seoul and Washington as a rehearsal for an invasion. In March last year, North Korea first made public a test of its underwater attack drone, the Haeil-1, claiming the "secret weapon" is capable of generating a "radioactive tsunami" and stealthily attacking enemies. In April, the country carried out a test of the Haeil-2 attack drone. /IANS