SEOUL, South Korea -- In power for barely more than a year, North Korean leader Kim Jong Un has adhered overwhelmingly to the policies of his father, using a familiar mix of internal repression and nuclear showmanship while all but dashing hopes that he would emerge as a Deng Xiaoping-style reformer.
Although analysts caution that Mr. Kim can still change course, the apparent status quo on policy carries dark implications, extending -- perhaps for a generation to come -- a government that relishes isolation, threatens its neighbors, values weapons over food for its people and keeps roughly 1 in every 120 of its citizens in gulags.
Tuesday's underground nuclear detonation, coupled with a recent long-range rocket launch and a string of fierce rhetoric toward the United States, represents a clear borrowing from the playbook of Kim Jong Il. And analysts say the young Mr. Kim, believed to be 30, has good reason to embrace his father's cold-blooded strategies. That's because Kim Jong Il succeeded on one count: He held onto power for nearly 20 years, even as he kept the nation destitute, and as other dictators across the world were overthrown or killed by rebels.
Kim Jong Il used his elaborate internal police network to snuff out rivals and dissenters. He banned outside information to keep people unaware of greater riches elsewhere. He used his country's nuclear weapons program to foster a sense of national strength, and at the same time occasionally extracted aid from the United States and its allies by making short-lived offers to curtail the program.
When Kim died in December 2011 of a heart attack, he was given an hours-long funeral, mourners thronging the city streets of Pyongyang, his hearse draped in a revolutionary flag. His youngest son then was named successor, the third in a family line that began with national founder Kim Il Sung.
"Kim Jong Il's policy worked," said Andrei Lankov, a North Korea expert at Seoul's Kookmin University. "You can call it dysfunctional, but Kim Jong Il was a winner and a survivor. ... If Kim Jong Un follows [suit]," Mr. Lankov said, "he might still live and rule for many, many years."
For several months last summer, there were signs -- reported by visiting diplomats and by defector groups with informants in the North -- that Kim Jong Un was experimenting with modest agricultural reforms that would allow farmers a greater chance to make private profits. Those reports coincided with a notable attempt in North Korea's state-run media to portray its young leader as a jovial man of the people, surrounded by a well-dressed wife, visiting amusement parks and attending pop music performances.
Months later, analysts and defectors say, there is little evidence that any limited capitalism has taken root. Meantime, the media portrayal -- though purposeful in image-building -- appears unrelated to Mr. Kim's policy preferences. Last July, North Korea's own state media said it's a "foolish and silly dream" to expect reform.
"It was a case of wishful thinking," said Bruce Klingner, a Korea specialist at the Heritage Foundation and a former North Korea CIA analyst. "If anything, Kim seems more belligerent than his father was."
A year ago, North Korea reneged on an accord with the U.S. to halt weapons tests in exchange for food aid. Since then, the North has launched two long-range rockets, detonated a nuclear weapon, threatened assassination of the South Korean president in its state-media and vowed to abandon its nuclear program only if every other country also gave up its nuclear weapons. Media reports suggest that the North also continues to ship missile or nuclear parts to Syria and Iran.
North Korea seemingly has become more dangerous than it was under Kim Jong Il, who came to power in 1994 after Kim Il Sung's death. The North's latest nuclear test was its most powerful. Its December rocket launch was the first successful attempt, following three failures, to send a satellite into orbit. (There was an additional failed launch with no satellite.) The country has also drastically increased border security, slicing nearly in half the rate at which defectors have been able to reach South Korea.
It remains unclear whether Mr. Kim is solely responsible for the North's major decisions over the past year. Some analysts think he receives crucial guidance from a small team of family confidantes, including his uncle and aunt. Others say he has quickly built up his individual power, and they point to the fact that four of the eight elder leaders who accompanied Kim Jong Il's hearse 14 months ago have since been removed or demoted.
When it comes to rocket launches and nuclear tests, North Korea's state media tries to give full credit to Mr. Kim. Photos released by North Korea last December showed him in what appeared to be a mission control room; he was watching a large-screen panel. Following the nuclear test, North Korea again paid homage to Mr. Kim, showing a series of interviews on state-run television with residents of Pyongyang, presumably reciting state-approved talking points.