By Heejin Kim
SEOUL, Dec 25 (Reuters) - North Korean leader Kim Jong Un oversaw the test-firing on Wednesday of long-range surface-to-air missiles at a launch site near its east coast, state media KCNA reported on Thursday.
The test, aimed at assessing the nuclear-armed country's strategic technology for developing a new type of high-altitude missile, destroyed targets in the air from 200 km (124 miles) away, KCNA said.
Kim also observed construction work at a separate site on an 8,700-ton nuclear-powered submarine capable of launching surface-to-air missiles, KCNA said. It did not identify the location or the date of his visit.
The submarine project is part of the North Korean ruling party's effort to modernise the country's Navy, one of five key policies the party is pushing to develop its defence capabilities, KCNA said.
Kim was quoted as saying that the all-out development of nuclear capabilities and modernisation of the Navy are essential and inevitable, while "the present world is by no means peaceful".
Kim also said South Korea's plan for developing a nuclear submarine, agreed with Washington, would further inflame tensions on the Korean Peninsula and poses a risk to national security that requires him to take action.
In a separate statement, North Korean state media criticised the recent entry of a U.S. nuclear-powered submarine into a South Korean port, calling it "an act of escalating military tensions" on the Korean Peninsula and in the region.
On Tuesday, the nuclear-powered submarine USS Greeneville arrived at the Busan port for crew shore leave and the loading of supplies, the South Korean Navy said.
North Korea also said earlier this week that Japan was showing its intention to possess nuclear weapons, encouraged by South Korea's moves to develop a nuclear submarine.
(Reporting by Heejin Kim; Editing by Chris Reese and Edmund Klamann)
