South Korea’s force of indigenously developed ballistic and cruise missiles may be the most underappreciated set of weaponry in Asia.

With little publicity, this strike-missile capability has been growing for decades, and it’s poised to surge following the end of a deal in which Washington and Seoul agreed to limits on what South Korea could develop.

South Korea has a family of Tomahawk-like cruise missile designs that can fly as far as 1500km against land targets. It also has a variety of ballistic missile types of increasing range and payload capacity, with one forthcoming weapon to be capable of submarine launch and another, for land-launch, with a range in the intermediate category, meaning 3000km to 5500km.

Official statements from Seoul consistently present the far-reaching strike-missile capability in terms of retaliation against North Korea, even though no part of that country is farther than 500km from the border with South Korea.

The specific policy that the strike missiles are said to serve is Korean Massive Punishment and Retaliation, which would target such facilities as underground command centres and nuclear missile sites. National Defence Minister Shin Won-sik embellished that policy in October with one of his own called ‘Punish Immediately, Strongly and Until the End.’

‘If the enemy carries out military provocations, first, punish them immediately; second, punish them strongly; third, punish them until the very end,’ he said. South Korea could deter North Korea’s provocations if Pyongyang felt it had more to lose than to gain from attacking, he added.

South Korea’s indigenous cruise missiles share the family name Hyunmoo 3 and have progressed through successive versions (or types) called Hyunmoo 3A, 3B and 3C. They probably offer high precision, and are well-suited for counter-force targets such as military installations, critical infrastructure and command and control systems. Hyunmoo 3D is reportedly in development. These weapons can be launched from trucks or ships.

The Haesung 2 is a supersonic cruise missile for launching from ships.

Whereas cruise missiles fly like aeroplanes—sometimes very low, to avoid defences—ballistic missiles fly high and descend at enormous speed, which makes them hard to shoot down. They’re usually not as precise as cruise missiles, but their warheads can be very heavy, and the velocity of their arrival helps them penetrate earth and concrete.

The former agreement that the United States imposed in 1979 limited South Korean ballistic missile payloads to 500kg and ranges to 180km. The payload limit was removed in 2017 and the range limit in 2021.

The US agreed in 2020 that South Korea could develop space launchers with solid propellant. Such a rocket or its technology could be adapted to create an intermediate-range ballistic missile, especially since South Korea, already having medium-range types, has no immediate need for more of them. South Korea successfully tested a solid-propellant space rocket in 2022.

Scrapping of warhead restrictions has enabled South Korea to develop ballistic missiles that can carry heavier warheads to penetrate tunnels and destroy underground missile storage chambers. Such capability strongly supports its position in the military balance on the Korean Peninsula.

This year South Korea said it had developed and successfully tested the Hyunmoo V ballistic missile, which will reportedly carry independently targetable re-entry vehicles and manoeuvrable re-entry vehicles. The Hyunmoo 5 may have a range of 3000km and is termed a ‘monster missile’. South Korea is also focused on developing hypersonic glide vehicles, which present different challenges to defenders and could be launched by a missile such as Hyunmoo 5.

Hyunmoo 5 may be carried by an arsenal ship, whose purpose would be to serve as a mobile magazine and launcher, not as a combat vessel. Hyunmoo 5 also reportedly uses the cold launch method, improving its survivability.

The Hyunmoo 4-4 submarine-launched ballistic missile is under development. Weapons of that category are even harder to hit before launch than those carried in surface ships. Seoul is also working on a ship-to-surface ballistic missile with features similar to those of Hyunmoo 4-4.

Back on land, South Korea’s short-range ballistic missiles of the Hyunmoo 2 family can be viewed as strategic as well as tactical, because they could reach any target in North Korea.

Against all this, North Korea has only weak defences, though it is trying to modernise them. Its other countermeasure is attempting to destroy South Korean missiles before they are launched, though that task becomes much harder if they move on ships or submarines.