If North Korea launches a military strike against South Korea, how long could the totalitarian regime maintain high the attack?
The Korean peninsula is once again dealing with a heightened level of tension this month. South Korea is blaming a mine that maimed two of its soldiers on August 4 on North Korea. South Korea responded to the exploding mine by restarting propaganda broadcasts along the Demilitarised Zone (DMZ). The North Koreans then fired a rocket at a loudspeaker on August 20. An hour later, South Korea fired dozens of artillery shells at the rocket launch position. Presently, the two sides are negotiating to ease the strain.
South Korean President Park Geun-hye says she will be less tolerant of North Korean aggression, a stance that compounds the chances of escalation. North Korea also tends to react strongly against annual US/South Korea military exercises (August 17 – 28) which is a contributing factor in the heightened pressure.
The two sides are still technically at war and hostilities restarting is an ever-present fear. While both countries wish to avoid war, the sheer size of the military forces arrayed only a few kilometres from each other makes the question of how an invasion might occur is far from academic. The South Korean military is well trained and equipped. Only the Japanese and the US militaries field more capable combat units in the Asia Pacific.
Add to this strength the explicit and demonstrable assistance from United States Forces Korea (USFK) – the sub-unified command of United States Pacific Command - and an attack would be extremely costly for any invading force from North Korea, which also possesses a large and well-positioned military structure throughout the country.
Initially, the order of battle of a North Korean attack is likely to employ its massive amount of short or medium range artillery and missiles. The majority of these weapons are heavily concentrated along the DMZ. USFK predicts some of the longer-range batteries may also be in range of Seoul, although just how much ordnance would fall on the capital city is unknown.
USFK estimates 500,000 rounds of artillery shells could be fired in the first hour of combat from the North, accompanied by missile and airstrikes. In response, the first hour would also see significant air-to-ground strikes and missile attacks from USFK and South Korean forces. Countering the North’s artillery and airstrikes are a central priority for the South and would limit the damage to Seoul, but not before significant damage was inflicted. The main North Korean ground force would rely on tanks and troops. Moving across the DMZ, North Korean armour would take one of three main routes.
The first option is the road along the east coast of the peninsula. The distance between the mountains and the sea narrows in some places to the size of a large warehouse. These limitations suggest any large force of armour would be exposed to ships from the US 6th fleet and South Korean navy, as well as from the air. The second possible route, called the Kaesong-Munsan corridor, is on the other side of the peninsula. This is the floodplain of the Han and the Imjin rivers, and was North Korea’s invasion route in the war of 1950.
North Korean armour has already proved it can travel along this route without much obstruction. It does, however, require crossing the rivers, so military engineers will need to bring bridging equipment that will slow down an invasion force. However, about 20 kilometres south of the DMZ, South Korea has created the largest tank-trap in the world. Its existence is not classified and is clearly marked on every map. In order to keep it hidden from the North Koreans it is not officially referred to as a tank-trap. Instead it is called Seoul. A city of 14 million people may as well be a swamp for a tank army. So it is unlikely North Korea will take this route as it would be rendered immobile and vulnerable.
The third route relies on a valley in the middle of the peninsula called Ch'orwon. This valley begins inside the north, emptying out just south of the Seoul megalopolis. USFK estimates the route could handle large numbers of armour and artillery pieces making this the most likely invasion route. Yet it too has constraints. The valley is wide in the north but narrow in the south. Meaning the North Koreans if they travelled too far down this valley would eventually lose the ability to manoeuvre and become bottlenecked.
Even if Pyongyang could muster the political will, it is doubtful the regime could produce enough fuel or ammunition for its military to conduct a sustained campaign. Due to externally imposed sanctions and its self-imposed isolation from the world, the North Korean regime is always dangerously low on supplies, both for its military and the wider economy. Its military is considered first among equals and receives much of the country’s goods and energy services. But these are scarce and unreliable, indicating a sustained military campaign may not even last three days.
The North Korean air force mostly comprises older MiG aircraft (of the MiG-15/17/19/21 types), but includes small numbers of more modern MiG-23, MiG-29 and Su-25 aircraft. The aircraft deployed close to the DMZ are typically fueled at 25-35% capacity during exercises to avoid pilots defecting to China (a not unreasonable precaution). It is known that severe shortages of spare parts and poor maintenance mean much of its aircraft weaponry may not be functional at all. Low fuel supplies also limits training and flight time, bringing the competency of North Korean pilots into question as well.
North Korea’s military equipment is also old – an estimated 45% was designed in the 1960s, while the rest is much older – and would struggle to effectively fight any modern force. The International Institute for Strategic Studies suggests North Korea’s armoured forces possess enough combat hardware to equip perhaps ten US divisions, but have an actual capability equivalent to about 2.5 US armoured divisions.
“With infantry equipment added, North Korean ground forces possess an overall firepower equivalent to nearly five modern US heavy divisions”, according to research from the IISS. By comparison, the Iraqi army in 1990 could field up to six modern division equivalents. North Korean airpower, equivalent to six US air wings in size, corresponds to only two F-16 wing equivalents in estimated net capability. An air wing comprises of three squadrons, each squadron containing about 20 planes.
Nonetheless, despite shortages of spare parts, fuel and training, North Korea’s conventional capabilities do threaten large swathes of South Korea’s civilian population. It would also be unwise to discount the threat of chemical, biological, or even crude nuclear attacks on South Korea. North Korea’s nuclear threat is compounded with a series of relatively successful tests of a new generation of indigenous ballistic missiles capable of housing different payloads. However, those missile systems have not proven reliability and would be unlikely to be used in the event of war.
A photograph released last year of Kim Jong Un putting his Strategic Missile Forces on high alert caused alarm in the international media, but should be kept in context. A display board in the background apparently showed a series of missile trajectories terminating in the continental US and various American Pacific military bases such as Guam and Hawaii.
While Japan and South Korea are within range North Korean missiles, the US is largely out of range for even the longest-range missile, the Taepodong-2. This rocket may have an operational range of 6700 kilometres, putting it in range of the Alaskan peninsula at best. Tokyo is similarly concerned about uncontrolled tensions on the Korean peninsula. The Japanese have been rhetorically targeted by Pyongyang in the past and Japan is within range of a missile strike. The Japanese military are therefore impelled to become involved in a conflict early, compounding the threat for North Korea.
Given the lack of adequate North Korean military equipment and strategic surprise, and the severe constraints on invasion routes, any conflict would cripple the North Korean regime without being an existential threat to South Korea or its allies. The net assessment is that a ground invasion into South Korea from the north is highly risky and unlikely to be undertaken. While a serious miscalculation may spark a new conflict, the North has much more to gain by maintaining the status quo.