​​Pyongyang ups naval and air saber-rattling over Seoul's nuclear-submarine plan

By Kim Hee-su Posted : December 25, 2025, 10:24 Updated : December 25, 2025, 10:24
North Korea said it test-fired a new high-altitude, long-range surface-to-air missile over the East Sea on Dec. 24 as Kim Jong Un, chairman of the State Affairs Commission, looked on. [Photo=Yonhap]
SEOUL, December 25 (AJP) -North Korea on Thursday warned that U.S. and South Korean moves involving nuclear-powered submarines would destabilize the Korean Peninsula, as Pyongyang combined sharp rhetoric with fresh disclosures of naval and air-defense weapons development. 

 North's leader Kim Jong-un condemned South Korea’s plan to develop nuclear-powered submarines during what appeared to be a deliberately choreographed visit to a submarine construction site, according to the Korean Central News Agency.

Kim made the remarks while inspecting the construction of an 8,700-ton nuclear-powered strategic guided-missile submarine, calling Seoul’s submarine plan—agreed with Washington at South Korea’s request—an “aggressive act” that would worsen instability on the Korean Peninsula and violate North Korea’s security and maritime sovereignty. 

He said the Democratic People’s Republic of Korea (DPRK) - North Korea - would not alter its national security policy or principles for countering what it calls hostile forces, warning that any attempt to infringe on the country’s “strategic sovereign security” would be met with “merciless retaliatory attacks.”

Kim also reaffirmed Pyongyang’s commitment to strengthening its nuclear deterrent, describing the submarine project as an “epoch-making” upgrade that would significantly raise the level of war deterrence. He said North Korea would continue pushing the “nuclear armament of the navy,” signaling a drive to build a sea-based nuclear strike capability. 

KCNA’s repeated references to a “nuclear-powered strategic guided-missile submarine” underscore Pyongyang’s claim that it is developing a nuclear-fueled submarine equipped with strategic missiles, a project first disclosed in March following a decision at the 8th Congress of the ruling Workers’ Party. 

Kim said newly built attack destroyers and nuclear-powered submarines would sharply boost the combat capabilities of North Korea’s fleet. During the inspection, he also reviewed research on new underwater weapons and outlined plans to reorganize naval forces and establish new units, KCNA said. 
 
The nuclear-powered submarine USS Greeneville arrives at a naval base in the southeastern port city of Busan on Dec. 23, 2025. (Yonhap)

The escalation in rhetoric coincided with a separate statement from North Korea’s defense ministry condemning the recent entry of the USS Greeneville, a U.S. nuclear-powered attack submarine, into a naval base in Busan earlier this week. The visit was aimed at replenishing supplies and providing rest for crew members, according to the Republic of Korea Navy. 

In a statement dated Wednesday, the North’s defense ministry accused Washington of embedding a “grave nuclear instability element” into the region’s security environment. It said the repeated deployment of U.S. strategic assets was escalating military tensions and pushing the U.S.–South Korea alliance toward what it described as a “nuclear confrontation bloc.” 

The ministry also criticized Washington’s reaffirmation of extended deterrence for Seoul and its support for South Korea’s nuclear-submarine ambitions, saying the moves confirmed U.S. intentions to pursue a “nuclear-to-nuclear collision structure” with the DPRK. It warned of unspecified countermeasures in response to what it called U.S. “nuclear muscle-flexing.” 
This photo, published by the Korean Central News Agency on Dec. 25, 2025, shows an 8,700-ton nuclear-powered strategic guided missile submarine under construction. North Korean leader Kim Jong-un inspected its building site, the news agency said. (For Use Only in the Republic of Korea. No Redistribution) (Yonhap)

Adding to the display of military capability, North Korea disclosed on Thursday that it had conducted a test launch of a new high-altitude, long-range surface-to-air missile over the East Sea on Christmas Eve, with Kim observing. 

KCNA said the test, carried out by the Missile General Bureau, was the first launch intended to assess the tactical and technical performance of the air-defense system under development. The missiles struck and destroyed a simulated high-altitude target at a range of 200 kilometers, the report said, describing the test as part of routine efforts to upgrade national air-defense capabilities. Kim was quoted as congratulating those involved.

South Korea’s military said it had detected the launch. The Joint Chiefs of Staff said it had been monitoring signs of a missile launch in advance and tracked what appeared to be multiple surface-to-air missiles fired from the Seondeok area in South Hamgyong Province toward the East Sea at around 5 p.m. Wednesday.
The JCS said detailed specifications were under joint analysis by South Korean and U.S. intelligence authorities, adding that the allies remain on high alert and maintain the capability to respond decisively to any provocation under a robust combined defense posture.
 

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