The government is seeking to persuade the U.S. not only to extend the range of South Korea's missiles but to increase the size of the warheads it is allowed to mount on them.
Existing missile guidelines signed by South Korea and the U.S. in 1979 and revised in 2001, limit the range of Seoul's ballistic missiles to 300 km and their payload to 500 kg, and any longer range would require their payloads to be reduced.
That way South Korea has been effectively prohibited from developing solid fuel-powered rockets that can be turned into mid to long-range ballistic missiles.
But now Seoul feels the threat from North Korea and the regional arms race make these restrictions dangerous and obsolete. In the next round of talks with Washington to revise the missile guidelines, it plans to raise both the issues of boosting the range and scrapping limits on payloads, a government source said Wednesday.
Military officials recently unveiled the Hyunmu-3 cruise missile with a maximum range of between 500 and 1,500 km, whose payload must under the existing missile guidelines be reduced if the range is extended.
If the size of the payloads is increased, it will be possible for the country to develop unmanned aerial vehicles that can be mounted with larger warheads or missiles.
Solid fuel-powered rockets can be launched immediately, but filling missiles with liquid fuel takes time.
The government has been in talks with the U.S. officials to extend the maximum range of ballistic missiles from 300 km to between 800 and 1,000 km. But Washington has dug in its heels.
Meanwhile, Kim Tae-hyo, the presidential secretary for national security strategy, arrived in Washington D.C. on Sunday for closed-door meetings with U.S. National Security Council and State Department officials to discuss responses to North Korea's nuclear test and missile development, as well as revising the missile guidelines.