For Alexandre Mansourov, a North Korea expert and visiting scholar at John Hopkins University, Kim's personal inexperience is worryingly matched by the outside world's inexperience in dealing with him
"Although he practiced brinkmanship all the time, there was a record of Kim Jong-il stepping back from the brink. We knew basically where his limits were, where his brakes were and what buttons to push to keep him behaving."
"With his son, we don't have a track record yet. We don't know what his limits are, how far we can push him or whether he has any brakes or not," he said.
In South Korea, which has more experience than anyone of North Korea's mercurial behaviour, analysts say what others see as reckless "adventurism" on Kim's part may in fact be well-calibrated pragmatism.
A South Korean elderly woman looks at a military barbed wire fence covered with hanging "reunification ribbons" at Imjingak peace park near the demilitarised zone (DMZ) dividing the two Koreas in the border city of Paju. AFP
"Kim only had a short time to prepare for leadership, which meant he had to move all the faster and more aggressively when it came his way, to secure his control on the power elite," said Chang Yong-Seok, senior researcher at the Institute for Peace and Unification at Seoul National University.
"It's not so unusual. Kim Jong-il was still solidifying his status as successor when he declared a semi state of war at the height of the first crisis over the North's nuclear programme in 1993-94," Chang said.
In a regime whose inner workings are as opaque as North Korea's, there have inevitably been questions as to whether Kim is really in charge at all – or is just a puppet manipulated by a coterie of top generals and officials. More: The Madness of King Kim Jong Un
Yang Moo-Jin, a professor at the University of North Korean Studies in Seoul, dismisses such speculation outright.
"I believe he has shown himself to be in full control of the party and the military," Yang said, pointing to Kim's "resolute" and even ruthless purge of top officials after he came to power.
"It's true that he's surrounded by a group of experienced mentors, but that doesn't make him weak. He's making the decisions on important state affairs. The system has been always like that," he added.
Where, then, is he taking the country?
Kim has followed his father's playbook of engineering a crisis and then sharply driving up the stakes to a level where a skittish international community offers concessions to lower tensions.
But it's a worn playbook, and this time a dry-eyed and unblinking United States and South Korea have chosen to stare Pyongyang down. More: North Korea aggression could strengthen US-China bond
Daniel Pinkston, a North Korea expert with the International Crisis Group, suggests Kim is waiting for joint South Korea-US military drills to conclude at the end of April.
"Its important to understand that a lot of what we see and hear – the photos of Kim hunkered with his generals in a war room, the apparently irrational threats – are largely meant for a domestic audience," Pinkston said.
The rhetoric from Pyongyang, Pinkston noted, was largely couched in the language of deterrence, with Kim portrayed as the leader standing between the North Korean people and US invasion.
"When the drills end, the message will be: 'Look. They were going to invade us with their B-52s and and their stealth bombers, but they didn't because of our nuclear deterrent and, above all, because of out saviour, the great marshal Kim Jong-un'. More: Will target your factories, North Korea tells South
"That's how it works," Pinkston said.