North Korea said its latest missile tests involved a new weapons system of major significance, with images suggesting the launch of a missile it has previously described as hypersonic.

Kim Jong Un said the weapon would strengthen North Korea’s military readiness, while observing the tests alongside his teenage daughter.

South Korea said it detected two short-range missile launches that traveled about 450 and 600 kilometers toward the sea, though North Korea reported longer range and different performance figures.

The launches are part of a series of North Korean weapons demonstrations as Kim continues developing nuclear-capable missiles and tensions with South Korea remain high, the AP has reported.

South Korean President Lee Jae Myung expressed hope that renewed U.S.-North Korean diplomacy could reopen dialogue and eventually lead to progress toward denuclearization.