By Heejin Kim SEOUL, - 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 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.