N. Korea builds up Kim Jong Un as nuke visionary PYONGYANG, North Korea - North Korea on Friday credited new leader Kim Jong Un with spearheading past nuclear testing, as it adds to a growing personality cult that portrays the young son of late leader Kim Jong Il as a confident military commander. Kim Jong Un's youth - he's believed to be in his late 20s - and quick rise have spurred questions in foreign capitals about his readiness for leadership. But North Korea has dismissed such worries in recent days, saying Kim Jong Un worked closely with his father on military and economic matters. The North's official Uriminzokkiri website said Friday that Kim "frightened" the country's enemies by commanding nuclear testing in the past. North Korea tested nuclear devices in 2006 and 2009, but the website didn't specify which tests Kim oversaw. Uriminzokkiri described Kim Jong Un as "fully equipped" with the qualities of an extraordinary general, even during his years at Kim Il Sung Military University. The website also repeated the North's claim that he was involved in satellite launching but didn't elaborate. North Korea's linking of Kim Jong Un to past nuclear testing comes as it pushes for the resumption of long-stalled six-nation aid-for-nuclear disarmament talks that also include China, Japan, Russia, South Korea and the United States. Washington and its allies want the North to first show it is serious about previous disarmament commitments. North Korea last week questioned Washington's generosity and sincerity, but suggested it remains open to suspending its uranium enrichment program if it can get the food aid it wants. Kim Jong Un took over after his father and longtime ruler Kim Jong Il died in mid-December and has quickly been given many of the country's most important titles. He was introduced as heir only in September 2010. Before that he had been kept out of the public eye for most of his life. He was quickly promoted to four-star general and named a vice chairman of the Central Military Commission of the Workers' Party of Korea. Some of North Korea's neighbors and Washington have expressed worry about whether he can lead a nation of 24 million with a nuclear program as well as chronic trouble feeding all its people. Kim Jong Il had 20 years of training under his own father, Kim Il Sung, before taking over. Even after his father's 1994 death, Kim Jong Il observed a three-year mourning period before formally assuming leadership. A senior official told The Associated Press recently that Kim Jong Un spent years working closely with his late father and helped him make key policy decisions on economic and military affairs. North Korea has also made it clear that Kim Jong Un will continue Kim Jong Il's "songun," or military-first, policy, and a steady stream of reports and images from state media has sought to show him as a fearless military commander who is comfortable with leadership. North Korea also reported Friday that Kim Jong Un inspected two more military units. Earlier this month, North Korea's state-run broadcaster aired a documentary that showed Kim Jong Un observing an April 2009 launch of a long-range rocket. It was the first indication of his involvement in the launch. The documentary quoted Kim as threatening to wage war against any nation attempting to intercept the rocket, which North Korea claimed was carrying a communications satellite but the United States, South Korea and Japan said was really a test of its long-range missile technology.