A South Korean soldier looks north at a guard post, just south of the demilitarized zone separating the two Koreas. (Yonhap via Reuters)

While little is known about Kim’s son and heir-apparent, Kim Jong Eun, U.S. officials and weapons experts see little to reason to believe that he will be any less enamored of the bomb.

North Korea’s first successful test of a nuclear weapon in October 2006 was a watershed moment for the communist state, the result of decades of work dating back to at least the early 1950s. Today the country’s tiny arsenal—estimated to consist of perhaps a half-dozen bombs—is both a matter of immense pride and an insurance policy for a regime that sees itself threatened by much larger countries, including the United States.

U.S. intelligence and military officials are not expecting dramatic changes in the country’s nuclear posture, regardless of whether the younger Kim emerges as absolute leader or shares power with members of the military elite. But government officials and security experts acknowledge that the transition period will be a time of uncertainty and increased risks. They also say that North Korea’s new leaders will not be easily persuaded to bargain away such a hard-won asset.

“Everything is quiet now, but at the first sign of instability, the immediate question is going to be who’s really in control of the nukes,” said Victor D. Cha, senior adviser and Korea Chair for the Center for Strategic and International Studies, a Washington think-tank.

In the security realm, “there’s really no situation worse than this: to have the most opaque regime with nuclear weapons and without a clear leader,” Cha said. “It doesn’t get more dangerous than that.”

Reliable intelligence of the state of North Korea’s nuclear program has been notoriously difficult to obtain, especially since 2003, when Kim Jong Il kicked U.N. nuclear inspectors out of the country and ended a “freeze” in weapons development that had been negotiated a decade earlier under the Clinton administration. At the time the freeze ended, North Korea had enough plutonium, contained inside irradiated nuclear fuel rods, for up to six nuclear bombs.

The nuclear device tested by North Korea three years later was unimpressive—the explosive yield was so small that many analysts concluded that the bomb had malfunctioned. But North Korea performed a second, more successful test in May 2009, and also announced that it had begun ramping up both its plutonium production and a previously undisclosed program to make enriched uranium.

In the weeks before the elder Kim’s death, North Korean news media bragged of “leaping progress” it its nuclear efforts, suggesting to many experts that a third nuclear test might be in the works. Pyongyang also warned other nations against interfering with its affairs and threatened to turn the South Korean capital into a “sea of fire.”

Staff writer William Wan contributed to this report.

View Photo Gallery: After years of speculation on his declining health, North Korean television has reported its leader, Kim Jong Il, has passed away. He was 69.

Read more about North Korea:

Death of Kim Jong Il dims hopes for U.S. talks

- Kim Jong Eun to be the ‘Great Successor’

- North Korea’s future unclear in post-Kim era

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