North Korea said Wednesday that it had test-fired an upgraded large-caliber multiple rocket launcher system the previous day under the observation of leader Kim Jong-un.

The North’s state-run Korean Central News Agency(KCNA) reported that the Missile Administration conducted the test on Tuesday to verify the effectiveness of an upgraded large-caliber multiple rocket launcher system incorporating new technology.

KCNA reported that four rockets fired during the test hit a maritime target about 358-point-five kilometers from the launch point and released photos from the test site. 

Kim’s daughter, Ju-ae, was also present at the launch.

Kim expressed satisfaction, saying the launch was important to strategic deterrence.

He added that the upcoming ninth congress of the ruling Workers’ Party would unveil future plans to strengthen nuclear war deterrence.

South Korea’s Joint Chiefs of Staff said on Tuesday that it had detected multiple ballistic missiles launched from areas north of Pyongyang toward the East Sea at around 3:50 p.m., adding that the missiles flew approximately 350 kilometers.