This picture taken on March 22, 2023 and released by the Democratic People's Republic of Korea's official Korean Central News Agency on March 24, 2023 shows one of the "Hwasal" strategic cruise missiles being launched in Hamhung City of the South Hamgyong province. (PHOTO / AFP)

SEOUL – The Democratic People's Republic of Korea (DPRK) conducted a new underwater attack weapon system test from Tuesday to Thursday in response to the "grave challenging situation against the state security of the DPRK" caused by a US-Republic of Korea large-scale war drills, reported the official news agency Friday.

The underwater nuclear attack drone, named "Haeil," has undergone more than 50 shakedown tests for the past two years, the Korean Central News Agency (KCNA) reported.

The test verified the weapon's reliability and safety and fully confirmed its lethal strike capability, the Korean Central News Agency reported

On Tuesday, the attack drone was deployed for a drill off the coast of South Hamgyong province, and "reached the target point in the waters off Hongwon Bay set as a mock enemy port with its test warhead detonating underwater on Thursday afternoon after cruising along an oval and pattern-8 course at an underwater depth of 80 to 150 meters" in the sea for 59 hours and 12 minutes, said the report.

The test verified the weapon's reliability and safety and fully confirmed its lethal strike capability, it said.

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The mission of the attack drone is to "stealthily infiltrate into operational waters and make a super-scale radioactive tsunami through underwater explosion to destroy naval striker groups and major operational ports of the enemy," said the report, adding that it can be "deployed at any coast and port or towed by a surface ship for operation."

Meanwhile, the DPRK on Wednesday conducted a launching drill to let strategic cruise missile units get familiar with the procedures and processes, it said.

Top DPRK leader Kim Jong-un guided the above military activities, said the report.