A renowned U.S. professor Wednesday stressed the importance of more "grassroot" contacts between the two Koreas to promote trust-building on the divided peninsula as there is no hope for eliciting exchanges at the government level.

Francis Fukuyama, a senior fellow at Stanford University, said realistically, it is not easy to expect cross-border civilian exchanges on the peninsula like those between East and West Germany in the past, but he said that economic liberation in the North can serve as a starting point for changes.

"The question is whether you can have more grassroot kind of trust-building where ordinary citizens have some interactions or a little bit more contacts. That's the only way that the North Korean society will change," Fukuyama said during an interview with Yonhap News Agency.

The professor pointed out that changes in North Korea are unlikely anytime soon.

"I think the North Korean regime is not going to let their citizens have that exposure to the outside. But the main hope is that if there is some degree of economic reforms or liberation, simply in order to promote economic changes, they (North Korea) are going to permit more contacts with the outside world," he added.

Fukuyama was in Seoul Wednesday for a forum on inter-Korean unification.

The professor said he saw the North Korean regime under young leader Kim Jong-un as "very fragile," adding he is apparently seeking the "reign of terror" by killing disobedient senior officials.

"It could be a source of future instability," he added.

Touching on Seoul's punitive sanctions on the North, Fukuyama emphasized "strict reciprocity" in dealing with the case but also added that what's important is how the inter-Korean policy is going to move forward.

Since May 2010, South Korea has imposed punitive sanctions on North Korea by banning economic and cultural exchanges to punish the North's torpedoing of the South Korean warship Cheonan in March of that year.

"If they show any signs or any interest in improving the relations, then you should reciprocate. But if they do something like sinking another ship or doing something very aggressive, you should respond forcefully," Fukuyama said.

He said that North Korea ultimately needs to take some accountability for the deadly sinking, but the issue should not dictate inter-Korean ties. (Yonhap)