PYONGYANG, June 23 (Xinhua) — The Democratic People's Republic of Korea (DPRK) on Thursday announced that it has successfully test-launched a surface-to-surface medium- and long-range strategic ballistic missile Hwasong-10 and the top leader Kim Jong Un watched the launch on the site, according to state media KCNA.

The ballistic missile "took off a self-propelled launching ramp and accurately landed in the targeted waters forward 400 km after flying to the maximum height of 1413.6 km along the planned flight orbit," the KCNA said.

The test-fire confirmed the flying kinetic feature of the DPRK ballistic missile with an updated system and its safety and control and the technical specifications of newly-designed rocket structure and its dynamic system, according to the state media. The test also verified heat-resistance of a warhead in its re-entry section and its flight stability.

Kim gave the order to start the missile launch after hearing a report on the plan. He was satisfied with the test results.

Kim said that the DPRK surely has the capability to attack the Americans in the Pacific region and that the country should have the powerful offensive means to pose a threat to the enemy and to defend its people from U.S. threats and other hostile forces.

He also stressed the need for the DPRK to increase its "preemptive nuclear attack capability in a sustained way" and to continue to develop strategic attack weapons, adding that the nuclear attack capability should be steadily bolstered to protect the country and the people from U.S. nuclear threat.

On Wednesday, South Korea's Joint Chiefs of Staff said the DPRK launched two ballistic missiles which were suspected to be intermediate-range Musudan missiles near the Wonsan area on the eastern coast.

The first was launched at about 5:58 a.m. Seoul time (2058 GMT Tuesday), but it appeared to have failed as the missile flew in an abnormal trajectory in a distance short of what a normal ballistic missile can fly. The DPRK test-fired a second missile at about 8: 05 a.m. Seoul time (2305 GMT Tuesday), which flew about 400 km. It is believed that a ballistic missile is required to fly at least 300 km to be considered successful in test-firing.

The latest intermediate-range missile launch was the sixth test-firing of its kind by Pyongyang after the five earlier launches were all believed to have failed.

The first test-launch of the missile on April 15 failed as the missile exploded in mid-air several seconds after take-off. The April 28 launch also failed as those exploded in mid-air or crashed in waters. The fourth test was estimated to have exploded on its mobile launcher even before take-off, according to the South Korean military.

Seoul did not clarify whether the sixth launch was a success or not, but said that Pyongyang has made progress in the development of ballistic missile technology.

The Musudan missile, known to be capable of hitting part of the U.S. territory such as Guam and the outer reaches of Alaska, has been deployed by the DPRK since 2007.

The missile was first revealed to the public in a military parade in 2010 celebrating the 65th anniversary of the Workers' Party of Korea. The April 15 launch this year was the DPRK's first known test-firing of the intermediate-range ballistic missile.