In such a setting, Mr. Kim’s trip to a border island on a wooden boat — it almost seemed designed to create a “Washington crossing the Delaware” motif — is proof of his “daring and pluck,” as the country’s main party newspaper, Rodong, explained. Rodong also declared about North Korea’s nuclear weapons: “Let the American imperialists and their followers know! We are not a pushover like Iraq or Libya.” The first, famously, had no nuclear weapons; the second gave up its nascent nuclear program in late 2003, a move North Korea describes as Col. Muammar el-Qaddafi’s greatest mistake.

In the propaganda world that the three generations of the Kim dynasty has created, Mr. Kim is “a great iron-willed general admired by all of his people, including real generals who have actually served in the military,” said Lee Sung-yoon, North Korea specialist at the Fletcher School of Law and Diplomacy at Tufts University. “For the Kim III, fantasy is reality.”

Keeping the fantasy up has required a lot of work in the past month, with many visits to military units on both of the country’s coasts, and a lot of conferences at midnight with generals.

Yet in each of these scenes, North Korea’s propagandists sometimes made Mr. Kim look as much a clumsy actor as a new leader of one of the world’s most belligerent governments.

For one, North Korean state-run media on March 12 released a photo showing Mr. Kim arriving at an island within the gun range of South Korean marines and quoted him as threatening to “cut the windpipes of the enemies.” But it strained credibility that he traveled to a region he called a powder keg on a small unarmed wooden boat, as shown in the photo.

On Tuesday, North Korea released a photo showing Mr. Kim watching hovercrafts storm a snow-covered beach in eastern North Korea. But it did not take long for journalists and analysts to conclude that the picture was clumsily doctored to add more amphibious landing vehicles and make the drill look far more imposing than it really was.

Then on Friday, photos released by the North’s state media, which also showed signs of digital manipulation, featured Mr. Kim huddling with his top generals during a midnight meeting to approve “plans to strike the mainland U.S.” A military chart behind them showed a series of lines shooting out of North Korea and hitting major cities in the United States, including those on the East Coast. Even if the North Koreans had such missiles — most analysts doubt it does — would they really intend to launch them at the United States in what would be a suicidal action for the Pyongyang government?