July 18, 2024: In North Korea there was recently more activity at the Sinpo shipyard with the revelation that work was nearly complete on the “Hero Kim Kun Ok” ballistic missile submarine SSB (diesel-electric powered ballistic missile carrying submarine) as well as the “8.24 Yongung” experimental SSB. The older submersible missile test stand barge was still present and available for missile tests.

Evidence from commercial satellite photos indicates that North Korea is planning to send their new SSB to sea with its SLBM (submarine-launched ballistic missile). Since the 1990s North Korea has been trying to design and build a working SSB along with a functional SLBM to launch from their SSB. The way these things work in North Korea is that there are usually decades of slow progress followed by several failed tests before there is actually some sort of success.

North Korean leader Kim Jong Un seems determined where his father had failed in developing an armed SSB that could be used to threaten South Korea, Japan and even the United States. These nations have far more advanced and actually functioning submarines and anti-submarine technology. Then there are the Americans’ BMD (Ballistic Missile Defense) systems at work in Ukraine for two years. South Korea and Japan also have these BMD systems. This makes the success of any North Korean SLBM unlikely. Japanese and South Korean ASW (Anti-Submarine Warfare) technology is also more than North Korean submarines can handle. South Korea has developed exceptionally efficient ASW since a 2010 incident where a North Korean submarine torpedoed and sank a South Korean corvette, killing 46 sailors. North Korea denied responsibility, but South Korea salvaged the corvette and fragments of the torpedo that sank it. Identifying marks on the torpedo revealed it to be North Korean. While North Korea continued to deny responsibility the incident encouraged South Korea to greatly increase its ASW capabilities.

None of this has discouraged North Korean leader Kim Jong Un from using a significant portion of North Korea’s resources on providing potential target practice for South Korean, Japanese and American ASW and BMD systems. Despite this dismal situation, North Korea keeps trying and their two new SSBs may actually go to sea and attempt to launch missiles.

The North Korean effort to build a usable SSB goes back at least a decade. In 2019 North Korea carried out another SLBM test from an east coast shipyard using a submerged barge to simulate launch from a submerged sub. The first test was in 2017. Both tests apparently used the cold launch capability of the Polaris 1 (KN-11) SLBM. Cold launch enables igniting the rocket motor after the missile has been ejected with a gas charge from its launch tube and into the air. This is essential for SLBMs when launched from a submerged sub. The first cold launch test occurred in 2016 and was not a success but whatever was wrong has apparently been fixed.

The Sinpo shipyard, where these tests take place, is also where North Korean SSBs are being built. This was confirmed in early 2015 when aerial photos clearly showed, despite a camouflage net, an SSB under construction. In 2015 it was believed North Korea could have an operational SSB that was carrying reliable missiles by 2018 if they completed and successfully tested the new 2,000 ton SSB being built as well as the SLBM the sub would carry. That did not happen but satellite photos show the construction of the sub was still going on and the SLBM seemed to be working. This is not surprising because there have been a lot of tests.

Since October 2014 there have been twelve test launches of the Polaris 1. Also known as the KN-11, all tests took place off the east coast. The first two tests, one of them a failure, were from land-based silos to test the silo container and especially the ejection mechanism. Test 4 in January 2015 was also from the land-based silo and was a success. There was another such test three months later, also a success. Test 6 in May 2015 was similar to the last previous two and was also a success. Test 7 in November was from an underwater barge and was an ejection test that failed. Test 8 in December was publicized and showed an SLBM breaking the surface (from a barge, not a sub as North Korea claimed), the engine igniting and then the missile exploded. This one was a partial success. Test 9 in April 2016 was another partial success with the SLBM breaking the surface, igniting its engine and not exploding. However, the SLBM only went 30 kilometers because of a non-explosive propulsion failure. Test 10 was in July 2016 and showed an SLBM breaking the surface from what appeared to be a sub (but was again the barge), the engine igniting and then the missile exploded when it was about 10,000 meters high. This one was a partial success. Test 11 was in August 2016 and was apparently a success. The proof was a video that showed the missile breaking the surface, the rocket engine igniting followed by rapid movement up and away. Japanese sensors detected the missile impacting about 500 kilometers from the launch site.

Many of the early tests were from a submersible barge that was developed by Russia and first used in the 1960s. The last four were from what the North Koreans claimed to be a locally built Whale (Gorae) class sub. That turned out to be untrue and all these tests were, and still are, carried out from the underwater barge using a launch silo similar to one that will be installed on the SSB. The 2016-17 tests were not all successful but since the August 2016 test, it appeared the North Korean design was capable of doing everything an SLBM is supposed to.

All these SLBM tests also indicated the North Korean SLBM was clearly based on the 1960s Russian R27 SLBM. One major difference is that the North Koreans appear to have replaced the original storable liquid fuel engine with a solid-fuel rocket motor. While the latter requires less maintenance onboard and is more reliable, it has half the range of the R27, only about 1,000 kilometers compared to 2,000 kilometers. South Korean intel analysts pointed out that the current KN-11 design could accommodate a solid-fuel rocket motor capable of extending the range to over 2,000 kilometers. This would make KN-11s with nuclear warheads a threat if the North Korea SSB became operational. Such a diesel-electric sub could travel to a position off the American West Coast and hit a lot of valuable targets west of the Mississippi River.

There appear to be two North Korean SSBs. The first one is smaller and locally built. This SSB is apparently meant for testing the SLBM. That may have been the intention but apparently the first of several Sinpo Class SSBs were part of an ongoing effort to come up with an SSB design that could actually carry and launch two or three KN-11 missiles from somewhere close to North America, Based on what is known so far, it appears that North Korea may have moved from the first 1,200 ton Gorae/Sinpo Class design to a larger, over 2,000 tons, SSB design that could make it across the Pacific. The Sinpo 1 design had limited range and endurance. It was a 1,200 ton sub with one silo built into the sail. Sinpo 1 used a lot of elderly (1960s and 70s) Russian submarine tech, required a relatively large crew of about 60 and can only stay at sea for about 30 days at a time. This design was also noisy and easy to detect. It was believed that there would eventually be a larger Sinpo 2 or Sinpo 3 sub under construction. It was only in 2023 and 2024 that proof of this was obtained via commercial satellite photos because initial SSB work was done inside a large shed. The SSB had to eventually leave the shed to a more visible drydock where equipment could be installed. By 2024 there was photographic proof that North Korea had two SSBs, one of them ready for use and the other still being completed. Now the North Korean KN-11 SLBM has a suitable SSB to be launched from.

What North Korea went through to develop the KN-11 shows how difficult the process was. North Korea initially obtained all, or parts of, a Russian R-27 SLBM in the 1990s. The R-27 is a 1960s vintage tech that was replaced in the 1970s by more modern designs, but many of the unused R-27s produced were recycled for scientific research launches until 1990. Some 500 R-27s had been launched with an 87 percent success rate. It was believed that all or much of at least one missile was illegally sold as scrap to North Korea in the 1990s. This was deduced from the fact that, after the Soviet Union collapsed in 1991, North Korea bought a lot of discarded Russian weapons for scrap, none of which was supposed to be operational equipment. It was later discovered that some of the scrap was remilitarized by the North Koreans. Thus it was no surprise that the new North Korean Musudan ballistic missile looked a lot like the R-27. There are pictures of the Musudan mounted on a large truck that serves as transport and launcher, not a submarine. After 2016 there were several Musudan tests from land facilities before it was tested from a submarine.

Developing an SSB took a similar route. North Korea also received ten decommissioned Russian Golf class SSB in 1993, to be turned into scrap. The Golf class boats used the 16 ton R-21 SLBM, which is thinner and longer than the R-27 that replaced it, in the first Russian nuclear powered SSBNs, in the 1960s and 1970s. Foreign intelligence agencies have been watching North Korea carefully for signs that North Korea was working on an SSB but the only possibility found was one new submarine under construction. It did not look like a copy of the Golf class boats but did have a sail that might have held an R-27/Musudan type SLBM. In any event, this boat seemed to be under construction for a long time and largely hidden from view. The scrapped Golf boats enabled the North Koreans to examine the first generation SLBM launch equipment, in which SSBs fired missiles from an elongated sail structure that contained three SLBMs. The eventual appearance of the Sinpo class SSB and the KN-11 SLBM is another example of North Korea adapting decades old weapons so they could be built in North Korea. The only missing piece is a nuclear warhead small and rugged enough to fit into the KN-11 and actually detonate. North Korea says this is being worked on. Less was said about the SSB effort, which indicates, based on past North Korean performance, that there is a lot more to be done to produce a sub that could carry and launch KN-11s at targets in the western United States.

This does not seem to bother the North Koreans because the SSB/SLBM delivery system is seen as a backup for the preferred ICBM approach. While the SSB can be more easily tracked and destroyed before it gets within the launch range of North America, the U.S. already has anti-missile systems in place to intercept a small number of North Korean ICBMs. The SSB could get past those anti-missile systems and launch close to the North American coast. In any event, North Korea's nuclear weapons continue to have a hard time acquiring the ability to attack the United States.

North Korea had a lot of unofficial help from China. For example, in 2011 China revealed the first of a new submarine class, which was seen moving under its own power near the port city of Shanghai. The new boat is a Type 43 Qing class SSB that was being readied for sea trials. The Qing class boats have an elongated sail, similar to that found in the Russian Golf class boats, which contain vertical silos for ballistic missiles. Russia built 23 of these 2,800 ton diesel-electric boats. Each had three launch tubes in its elongated sail. The Golfs were in service from 1958-1990, and the last of them carried the 16 ton R-21 (SS-N-5) ballistic missile, which had a max range of 1,600 kilometers and carried a single nuclear warhead. North Korea received ten decommissioned Golf class boats in 1993, to be turned into scrap.

China bought the plans for the Golf class SSBs in 1959 and built one. This boat was believed retired, but it was later seen restored to service, apparently for testing China’s only two sub launched ballistic missiles, the Jl-1 and Jl-2. But the Chinese Golf was also testing the missile silo design for the new Qings.

China had lots of problems with its JL (Julang) 2 SLBM, and the SSBNs that carried them. The 42 ton JL-2 has a range of 8,000 kilometers and would enable China to aim missiles at any target in the United States from a 094 class SSBN (ballistic missile carrying nuclear subs) cruising off Hawaii or Alaska. Each 094 boat can carry twelve of these missiles, which are naval versions of the existing land based 42 ton DF-31 ICBM. China has not yet sent the 094s on confirmed combat cruises. The Chinese and American Navies keep quiet about such activities. All that is known is that the 094s are more difficult to track and the Chinese have apparently tried to conduct stealthy patrols in the eastern Pacific, where their SLBMs could reach most of the United States west of the Mississippi River.

The JL-2 was supposed to have entered service three years ago but kept failing test launches until there was a success. The Chinese Type 092 SSBN ever went on a combat cruise, because these boats were noisy and unreliable. The subsequent Type 094 SSBN was more successful and since 2020 six of these have been in service. The Type 094 is still noisy enough for Americans SSNs to track

The Qing class eliminates the troublesome nuclear power plant and appears to have AIP (Air Independent Propulsion). This means a Qing could submerge west of Hawaii and approach close to the West Coast of the U.S. and fire two or three JL-1 or JL-2 missiles, or maybe not. It’s unclear what the Qing class subs are for. They might be carrying new, longer range cruise missiles. Over the next few months, more details will emerge now that one of these new subs is in the water.