North Korea’s Mock Nuclear Strike on Seoul Could Mean Unprecedented Casualties

Last March, attention was drawn to how powerful a nuclear warhead would be if it exploded in the sky over Seoul, as it was confirmed that North Korea conducted a test to maximize the lethality of a short-range ballistic missile (KN-23) equipped with a mock tactical nuclear warhead by exploding it in the air at the height of 2,624 feet(800m).

At the time, the North Korean Central News Agency reported that the ‘North Korean version of Iskander (KN-23)’ ballistic missile, which puts the entire South Korea within its striking range, was equipped with a mock nuclear warhead and then exploded in the air, stating it was a “nuclear counterattack virtual comprehensive tactical training” and a “mock launch training for nuclear strikes against enemy key targets.” The typical method of a nuclear attack is to explode a nuclear warhead in the air. This report is interpreted as North Korea demonstrating its ability to use missiles equipped with tactical nuclear warheads in actual combat.

According to the report, a missile test launch was conducted in the Dongchang-ri area of Cheolsan County, Pyonganbuk-do. The media reported, “A comprehensive tactical training was conducted to master the process and procedures for performing tactical nuclear attack tasks,” and “The missile warhead launched that day exploded accurately at a height of 2,624 feet(800m) above the target in the East Sea, and the reliability of the nuclear explosion control device and the detonation device of the nuclear warhead part was verified.”

In response, a representative of the Korea Defense Research Institute said, “2,624 feet(800m) is the altitude that can maximize the killing radius when a nuclear warhead, which North Korea claims can be mounted on the KN-23, explodes, which could pose a significant threat to us.” It is unusual to publicly disclose the operating altitude of the detonation device during a missile launch. A military official said, “It set a typical ground nuclear strike target altitude.”

In particular, the media raised the threat level by revealing the specific flight specifications and operating procedures of the North Korean version of Iskander (KN-23) while conducting ‘nuclear counterattack virtual training.’

“The higher the nuclear power, the greater the damage when exploded at a high altitude”

If the media’s report is accurate, there is an analysis that there is a possibility that a small tactical nuclear weapon is more powerful than the atomic bomb Little Boy (15kt·kiloton·1kt is the destructive power of 1,000 tons of TNT), and Fat Man (20kt) that fell on Hiroshima and Nagasaki during World War II have been completed.

According to the nuclear explosion simulation site ‘Nukemap,’ if a tactical nuclear weapon with a power of 10kt explodes in the air at a height of 2,624 feet(800m) above Seoul City Hall, the estimated number of deaths is 44,000. Some experts analyze that a nuclear weapon optimized for an explosion at a height of 2,624 feet(800m) is more than 60kt, in which case the number of deaths is estimated to increase to 237,000.

Military experts evaluate that it is unusual for North Korea to specifically disclose the operating altitude of the detonation device during a missile launch. A military official said, “It set a typical ground nuclear strike target altitude.”

In fact, during World War II, Little Boy and Fat Man, which were dropped on Hiroshima and Nagasaki, Japan, respectively, exploded in the air at a height of 1,804 feet(550m). The United States set the explosion altitude to maximize the destructive power of the 15-20kt atomic bomb at the time. The higher the power of the nuclear bomb, the higher it needs to be exploded to cause more damage to the target, and tactical nuclear weapons are known to have a destructive power of 10-20kt.

Therefore, if a tactical nuclear weapon of this size explodes in the air at a height of 2,624 feet(800m) above Seoul City Hall, people within a radius of 0.91-1.31 miles could suffer third-degree burns from thermal radiation. The number of deaths is estimated to be between 44,000 and 115,000, and the number of injured is estimated to be between 300,000 and 420,000. A nuclear expert analyzed, “It seems that they set 2,624 feet as the explosion altitude to imply the development of a tactical nuclear weapon with a more powerful force than what was dropped on Hiroshima and Nagasaki,” and “It can be seen as a force that can reach more than 50kt.”

The results change if North Korea changes its target and aims at the presidential office in Yongsan, Seoul.

According to the results presented by the ‘Nukemap (Nukemap),’ a nuclear explosion simulation program developed at the Stevens Institute of Technology in the United States, if a missile carrying a 10kt (TNT explosive 1,000 tons power) tactical nuclear warhead is assumed to explode at the height of 1,312 feet(400m) above the presidential office in Yongsan, Seoul, the number of deaths is predicted to be 46,510, and the number of injured is 164,850. It is estimated that a crater will be created within a radius of 502 feet(153m) from the explosion point, and residential buildings within 0.84 miles are likely to collapse. If minor injuries are included, the final area of damage is estimated to expand to the south of the Han River, reaching 16.11 square miles, including the entire Dongjak-gu area.

The simulation result assumes a situation where a 20kt nuclear warhead, which can maximize its killing power at a height of 2,624 feet, explodes, resulting in about 114,600 deaths and a total of about 534,600 casualties. It was revealed that a radius of 3.29 miles (33.8 square miles), including the presidential office in Yongsan-gu (2.24 miles), is included in the direct damage area of the nuclear explosion. In this area, a giant mushroom cloud rises to a height of 4.47 miles, and it is expected that there will be a large number of casualties who will die from radiation within a month after the explosion within a radius of 0.72 miles, including the Seoul Government Complex and Myeong-dong.

It is estimated that people within a radius of 1.31 miles, including Yongsan-gu Huam-dong and Namsan Tower, will suffer severe injuries such as third-degree burns and the need to amputate parts of the body. More importantly, if a 20kt nuclear bomb explodes at a height of 2,624 feet above Yongsan, the presidential office, the Ministry of National Defense, and the Joint Chiefs of Staff will suffer damage to the extent that they disappear on the map. The area within a radius of 1.19 miles, including universities and apartments in Yongsan-gu, is directly exposed to building collapses and fire damage caused by a nuclear explosion.

20kt Nuclear Destruction Power, Over 115,000 Deaths

North Korea launched a long-range strategic cruise missile, presumed to be the ‘Hwasong-1·2 type,’ into the West Sea on September 2. North Korean media emphasized at the time that it had “detonated in mid-air at an altitude of 150m above the target island.” Military experts are speculating that this cruise missile could be the ‘Hwasong-1·2 type’ that North Korea is developing, which is capable of carrying a 10kt tactical nuclear warhead.

Recently, North Korea has frequently mentioned the term’ mid-air explosion’ in its public reports following missile test launches. It claims to have carried out nuclear strike missions by setting various mid-air explosion altitudes for missiles, ranging from 150m to 800m. Military experts are expressing concern about these activities. In this regard, the National Intelligence Service also mentioned in a report to the National Assembly’s Intelligence Committee that “there is a possibility of threats in this direction during future provocations against the South, as they are testing the power of tactical nuclear weapons.” It is said that they are finding the optimal altitude for a mid-air explosion that can produce the most effective nuclear killing effect, considering the targets and objectives in South Korea.

According to Nukemap, if a Hwasong missile carrying a nuclear warhead successfully explodes after infiltrating Seoul at a low altitude and surging up to 150m above Seoul City Hall, it is estimated that 69,910 people would die and 113,870 people would be injured.

Therefore, the effect can be increased by detonating at a relatively high altitude to widen the killing radius. On the other hand, to destroy sturdy facilities such as underground bunkers, it is more effective to lower the explosion altitude, even though the killing radius decreases. Nukemap predicts the optimal mid-air explosion altitudes to be 102m to collapse concrete structures with a 10kt tactical nuclear weapon and 1010m for the intention of causing injuries.

In March, North Korea publicly displayed a series of mid-air explosion test launches of missiles, along with a tactical nuclear cartridge ‘Hwasong-31 type,’ estimated to have a power of about 10kt. North Korea unilaterally claims that the Hwasong-31 type can be mounted on 8 types of missiles, including the KN-23·24·25 and Hwasong-1·2 type. It’s a show of their ability to operate tactical nuclear warheads like loading bullets into a gun.

What is certain is that they are conducting test launches with different strike purposes for each type of missile and simulating the power of mid-air explosions based on theoretical figures. In other words, North Korea is currently repeating actions to find the ‘most dangerous height’ that can cause the maximum human and material damage in South Korea.

So far, North Korea has conducted six nuclear tests. The most recent, the sixth hydrogen bomb test, was estimated to have an explosive power of 100~300kt. Researcher Yang Uk of the Asan Policy Institute said, “To prevent nuclear fallout from flying into North Korea, the North Korean military is likely to choose a time when the wind is blowing south when launching a nuclear attack on the South.”

This is because a considerable amount of energy is released in a nanosecond when a nuclear bomb explodes, causing a thermal storm of about 180 million degrees. Along with the atomic storm, thermal radiation and fallout spread due to nuclear fission, causing significant damage to the surrounding base areas. The direct damage radius from the explosion also reaches 2.65 miles.

Strategic Nuclear Launch Estimated 783,197 Deaths

The damage to human life is shown to increase even more in the event of an explosion of a much more powerful strategic nuclear weapon. If North Korea fires a single atomic missile (250kt class) towards Seoul, ’38 North,’ a U.S. North Korean specialist medium, estimated that it would result in tremendous damage of 783,197 deaths and 2,778,009 injuries. This is much larger than the scale of human casualties during the Korean War (deaths 373,599, injuries 229,625, kidnappings and missing 387,744) and World War II in Japan (deaths 500,000~800,000).

This medium simulated the future nuclear weapon power of North Korea up to a maximum of 250kt, seeing the power of the sixth nuclear test conducted by North Korea in 2017 as 108~250kt.

In other words, they divided the power range of one nuclear warhead into 15~250kt and calculated it for seven scenarios. The population of Seoul was set at 24,105,000. However, they took into account that the actual reliability of the missile system is difficult to reach 100%, and South Korea’s THAAD (Terminal High Altitude Area Defense) deployment against North Korea’s nuclear and missile attacks.

They simulated the possibility of North Korea’s nuclear weapons hitting the target (detonation rate) at 20%, 50%, and 80%, respectively.

If 20% of North Korea’s nuclear missiles hit, the human casualties in Seoul are predicted to be 220,000 deaths and 790,000 injuries when the atomic warhead power is 15kt, and 1,220,000 deaths and 4,330,000 injuries when the nuclear warhead power is 250kt. Also, in a 50% explosion possibility, the casualties are estimated to be 550,000 deaths (15kt standard)∼1,750,000 deaths (250kt), 1,980,000 injuries (15kt)∼6,230,000 injuries (250kt), and in an 80% situation, 880,000 deaths (15kt)∼2,020,000 deaths (250kt), 3,170,000 injuries (15kt)∼7,190,000 injuries (250kt).

A military official said, “If North Korea’s claims are true, it means that the practical use of ballistic missiles equipped with nuclear warheads is imminent,” but also evaluated that “North Korea may be exaggerating to give us a sense of threat.”

By. Lee Hyun Ho