According to the report published on Thursday, the new weapon can carry a warhead of up to three tonnes with a flight range of 350 to 400 km (217 to 248 miles).
The project went ahead after the full lifting of US-imposed restrictions on missile development.
“We will develop stronger, longer-range and more precise missiles so as to exercise deterrence and achieve security and peace on the Korean Peninsula,” the South Korean government said in a statement.
In its defence blueprint for 2022 to 2026, the defence ministry said it would develop new missiles “with significantly enhanced destructive power”, upgrade missile defence systems and deploy new interceptors against long-range artillery.
The missile would be the latest in a tit-for-tat conventional missile race between the two Koreas.
In 2020, South Korea announced its new Hyunmoo-4 short-range ballistic missile (SRBM) could carry a 2-tonne warhead, while in March North Korea tested an SRBM that it said could deliver a 2.5-tonne payload. The Hyunmoo-4 is South Korea’s largest missile.
“Following the termination of the guidelines, we will exercise deterrence against potential threats and improve strike capabilities against main targets,” the defence ministry statement said.
Before the decade is out, Asia will be bristling with conventional missiles that fly farther and faster, hit harder, and are more sophisticated than ever before – a stark and dangerous change from recent years, analysts, diplomats, and military officials have said.
Overall, South Korea’s defence blueprint calls for spending 315.2 trillion won (US$273bn) in the next five years, a 5.8 percent year-on-year increase on average, as it continues to bolster its defences amid threats from Pyongyang.
South Korea’s defence ministry said that in order “to shut out provocations at a long distance”, the country will “sharply increase the number of interceptors targeting mid- and long-range missiles,” as it seeks to develop its own interceptor system, similar to Israel’s Iron Dome.
To better detect such threats across the Korean Peninsula, the military will deploy additional missile early warning radar systems and strengthen its surveillance capabilities, it said.
The defence plan also seeks to expand Seoul’s presence in space with an eye to deploy a new radar system to monitor space objects by the early 2030s.
Meanwhile, its Navy also plans to build more 3,000-tonne or larger submarines to replace ageing frigates with new ones with improved operational and combat capabilities.