Park, who has been visiting North Korea for decades, said conditions for ordinary North Koreans remain bleak, though there is not the mass starvation the country suffered in the 1990s.
"Kim Jong Un's primary objective is to improve the economy by participating in the international market," Park said.
That's a feat that is not possible without U.S. cooperation.
"So he realized he has to improve relations with the outside world," Park said. "In the big scheme of things, Kim Jong Un must have thought that North Korea would be taken more seriously (after a rocket launch)."
Sigal said Kim has been consolidating his power for some time by sacking unwanted people from his Cabinet.
"Purge is too strong a word but there have been all sorts of changes," Sigal said. "That's telling me that this guy is taking charge and setting up for economic policy changes. Kim Jong Un staked his personal prestige on economic growth."
Sigal warned that at the moment, there were no signs of any economic changes.
Park, however, said he could see some evidence of the North Koreans boosting agricultural production, building hydraulic power plants and other infrastructure and inviting foreign investors. The Chinese, in particular, have taken advantage of that, Park said.
Sigal agreed that Kim Jong Un has shown signs that he wants to stimulate economic growth but the problem is that means he has to make a change from his father's military-first policy that devoted billions of dollars into weapons development.
"The question is does he have the political muscle and the political will to do that?" Sigal said. "He has certainly positioned himself to do that." In the world's most totalitarian state, it's difficult to predict the future.
But the rocket launch this week certainly cast the spotlight back on the enigmatic nation and served as a reminder to global powers that the North Korean problem isn't just going to slither sway.
"He's saying to the world, 'Look, I'm back,'" Richardson said about Kim Jong Un. "You can't keep me off the headlines. I have to be dealt with. This is the capability I have."
Richardson believes the main message this week has to be that the United States and the four other countries that have been involved in talks with North Korea -- China, Japan, South Korea and Russia -- have to come up with a new approach in their dealings with Pyongyang.
"These guys are serious; they've got missiles now," Richardson said.
"It's uncertain about the new leader," he said. "I'm disappointed, because I thought maybe there's a positive political opening with him."
Maybe there still is.
Sigal said the only way to get what Washington wants on the nuclear front is to come to the table. It's also the only way to know more about North Korea.
Sigal likes to say that there is only one thing tougher than negotiating. And that's not negotiating.