Kang and Cha said the question that should be asked about Kim is whether he is turning out to be adventurous or cautious.
A risk-taking leader "may or may not be good for North Korea and its relations with the outside world," they say. Any major changes in foreign policy would bring "enormous hazards." Domestic, economic and social reforms also involve risks, they said.
"If Kim moves beyond the political theater of the past 60 years -- chest-thumping, name-calling, threatening to turn Seoul into a 'sea of fire' -- and actually risks a major military strike against South Korea or even the United States, he is putting his own neck, as well as his country's, on the line," they wrote.
What if Kim plays it safe?
"A cautious Kim, who simply pursues the status quo, would mean that North Korean policy will muddle along, with no real change to the frustrating, dangerous, decades-long game of brinksmanship," they said.
What we don't know about Kim
Fred Kaplan, writing in Slate, said Kim Jong Il was schooled to take the reins of power. Kim Jong Un, however, "is still an unknown quantity."
Kim Jong Un "had no political or military experience before taking putative control of the army, the party, and the nation." The young leader "had little time to learn anything; his behavior is at best hard to read, and at times bewildering."
Kaplan cites an incident last year. President Obama agreed to provide North Koreans with food aid if they suspended missile and nuclear tests. But Kim embarked on a missile test before the food arrived. He touted the act after Obama canceled the food aid and got the U.N. Security Council to condemn the North Korean action.
He compares Kim Jong Un to his father and grandfather.
Kim Jong Il and Kim Il Sung "would make a threat, and wait for the enemy (the United States, South Korea, the U.N., or some combination of the above) to offer a bribe in exchange for their forbearance. They would take the bribe -- and they'd forbear," Kaplan writes.
"But this new Kim took the promise of a bribe -- then went ahead and carried out the threat anyway, even before the payment, in this case desperately needed food, came through. What the hell?"
People now want to know Kim "knows how to play his family's game," Kaplan said.
"It's always been an odious game, but in the old days, when the father and grandfather were around, it would end with peace, at least for a while, if the west played along," he said.