A War with North Korea Would Be a Conflict Like No Other (And Millions Could Die)
The North Korean attack would likely involve a classic 20th century combined arms assault, using artillery to disrupt RoK defenses and soften up positions (as well as create civilian panic), infantry to break holes in the South Korean lines, and mechanized forces to exploit those gaps. The North Koreans could well add special forces (potentially deployed to South Korea before the initiation of hostilities) and regular forces deployed by tunnel to South Korean rear areas.
The Korean People’s Air Force is ancient, and has received no significant infusion of Russian or Chinese technology in years. The force has very little counter-air capability relative to the Republic of Korea Air Force, and its fighters would find themselves easy prey for well-trained South Korean pilots flying sophisticated aircraft. The KPA can expect very little ground support, either on the tactical or operational scales, and would likely struggle under South Korean air attacks.
To remedy these problems, North Korea would likely reserve a large proportion of its land-attack cruise missiles and short-range ballistic missiles for attacks on South Korean air bases, in the hopes of destroying fighters on the ground and rendering facilities useless.
The Korean People’s Navy would play a dual role in the operation. Offensively, it would try to attack Republic of Korea Navy (ROKN) capital ships (including the Dokdo-class amphibs, and the Sejong the Great-class destroyers, the latter of which have anti-ballistic missile capabilities) with submarines and cruise missiles, while also attempting to disrupt port operations. Defensively, the KPN would try to protect North Korea’s coastline from bombardment and amphibious assault, both of which had a great impact on the 1950 war.
Any North Korean invasion would also include attacks on South Korean ports, both to disrupt trade and to complicate the arrival of large-scale reinforcements. These attacks would likely involve conventionally-armed ballistic missiles, although the DPRK might resort to nuclear or chem-bio weapons for some particularly lucrative targets (such as Busan).
With luck (and the North Koreans would need tremendous amounts of luck) the Korean People’s Army (KPA) could disrupt U.S. and RoK forces sufficiently to seize control of the major entry and exit points to Seoul, at which point it could consider either trying to roll up the rest of the peninsula, or hold for a negotiated peace that would leave the DPRK in a stronger position. This decision would hinge both on the tactical situation, as well as an assessment of whether North Korea’s national goals lie mainly in reunification, or in regime survival.
But Diplomacy Has a Role…
The longer the war continues, the grimmer North Korea’s prospects look. Consequently, Pyongyang needs the support of Beijing to end the war and secure its gains quickly.
Why would Beijing concede to act as guarantor of the fruits of North Korean aggression?
Not because of any lingering affinity with the North Korean regime, but rather out of a desire to prevent further disruption and instability along its border. Similarly, its frustrations with North Korea aside, China has little interest in the establishment of a U.S. or Japanese client across the whole of the Korean Peninsula.
In this situation, North Korea would hope that the prospect of war against China (and perhaps Russia) would deter the United States from pursuing the liberation of South Korea. This calculus is remarkably similar to that of Kim il-Sung in 1950, although in this case North Korea’s own nuclear arsenal (presumably directed at Japan) would provide some deterrent.
In Keeping the Peace...
This is the best case for North Korea, but it is important to recall that most analysts judge North Korea’s military as insufficient to defeat the forces of the RoK. The static defenses along the DMZ, combined with the mobility and sophistication of RoK forces, mean that any offensive into South Korea is likely to bog down into a logistical disaster before it can capture Seoul. At that point, attacks along the depth of the North Korean position, combined with a concerted assault on regime targets and the KPA’s command and control network, will likely isolate advance forces and leave them ripe for destruction.
The North Korean air defense network is immense and robust, but not particularly sophisticated. Even the much-vaunted artillery along the border will likely see quick attrition at the hands of hyper-accurate counter-battery attacks and other precision guided munitions. Once KPA forces are defeated in the field, there is little doubt that the ROK and the United States would take advantage of the opportunity to end the regime once and for all.