On Monday, January 29, the North Korean state media Rodong Sinmum reported that the day before for the first time, two Pulhwasal-3-31 cruise missiles were launched from the conventional strategic submarine Kim Gun-ok (number 841) of the Sinpo-C class SSB (Ship Submersible Ballistic). The test was watched by North Korean dictator Kim Jong Un, who announced a program to build nuclear-powered submarines.
The SLCM (Submarine-Launched Cruise Missile) missiles were launched at approximately 8:00 a.m. local time, when the ship was in the Sea of Japan (East Sea), near the Sinpo Naval Base in South Hamgyŏng Province. According to the information provided, their flights lasted 7,421 seconds (2:03:41) and 7,445 seconds (2:04:05).
The name Pulhwasal-3-31 was revealed during the first test test on January 24 (from land), but it has not yet been reported whether it was an SLCM-class missile. Therefore, the South Korean intelligence agency NIS (National Intelligence Service) speculated that it was a medium-range cruise missile.
Interpreting North Korean weapons nomenclature, Pulhwasal-3 can be classified as a missile type (like Whasal-2), and the number 31 is the designation of the warhead, which is presumably a Hwasan-31-type nuclear warhead.
It is believed to be the Kim Gun-ok submarine, which was launched on September 8, 2023, has four larger vertical ballistic missile launchers and six smaller cruise missile launchers.
As Rodong Sinmum reported in a press release, Kim Jong Un is personally leading the nuclear submarine building program, noting that equipping the Korean People’s Army Navy (KPN) with such capabilities is a very important task. It was also mentioned that the construction of nuclear-powered submarines was officially discussed, which allegedly confirms that North Korea is in fact developing nuclear marine propulsion. Kim Gun-ok is independently classified as an SSB-ship, which can only carry ballistic and cruise missiles, but has a classic diesel-electric propulsion.
Whether if this is true or not, it can be assumed that North Korea is at least conducting research and development works on nuclear marine propulsion, including reactor technology and reactor cores. However, it will be necessary to further analyze whether North Korean nuclear technology is of a high enough level, capable of miniaturizing reactors with a safe design and providing technology and materials for their development.