Defense minister Shin Won-sik said Tuesday that North Korea appears to have made "some progress" in its pursuit of developing a hypersonic missile based on the recent intermediate-range ballistic missile(IRBM) fired by the regime on Sunday.

Speaking in a radio interview with KBS, Shin said that in 2022, North Korea fired a liquid fuel hypersonic missile, but the most recent hypersonic missile test used solid fuel technology, showing some progress.

The defense chief also touched on recent reports of Seoul failing to conduct proper inspections of North Korea's demolition of guard posts inside the Demilitarized Zone, under a 2018 inter-Korean military agreement.

Shin said that there is a high possibility that the underground facilities of the North's destroyed guard posts were untouched, as the regime has recently been seen working quickly to restore them.

The two Koreas in 2018 destroyed ten guard posts each to follow through on the military agreement signed under the previous Moon administration to reduce tensions along the border.