North Korea's claims of hydrogen bomb development are technically unlikely for now, but the communist nation could deploy a single-stage thermonuclear weapon with a yield of 100 kilotons around 2020, a U.S. expert claimed Wednesday.
  

North Korean leader Kim Jong-un claimed last week that the country has become a "powerful nuclear weapons state ready to detonate a self-reliant A-bomb and H-bomb." It was believed to be the first time that Kim has publicly claimed development of an hydrogen bomb, which is much more powerful than conventional nuclear weapons.
  

But the White House effectively rejected the claims, saying U.S. intelligence "calls into serious question those claims." Officials in Seoul also expressed skepticism, saying Pyongyang is not believed to have such capabilities when it has not yet mastered the technology to miniaturize nuclear warheads.
  

Joel Wit, editor of the website 38 North, said during a press briefing that the North's H-bomb claim is "technically unlikely, but boosting yields with fusion fuels is not." He also said Kim's pronouncement states exactly what North Koreans have been saying for years.
  

"Every country that has built nuclear weapons has done that as next step in the development process," he said.
  

But beyond 2020, Wit said that the North could deploy a single-stage thermonuclear weapon with a yield of 100 kilotons and could make significant progress on a two-stage weapon. That yield is hugely more powerful than conventional nuclear bombs, considering the yield of the nuclear device the North last tested in 2013 was estimated at about 7 kilotons.
  

Wit also said the U.S. should accept the North's demand for peace treaty negotiations.
  

Pyongyang has stepped up the demand in recent months as the six-party nuclear talks have long remained stalled. The U.S. has flatly rejected the idea as a nonstarter as long as the North has nuclear ambitions. U.S. officials have stressed that should first focus on negotiations to end its nuclear program.
  

"Everyone thinks it's not serious," Wit said of the North's demand. "What I would say is let's find out if they're serious. Let's engage them on it. Let's say to them, 'Hey sure, peace treaty talks, happy to do it, but you have to address our issues too, denuclearization.'"
  

The expert said that one of the reasons for the North's development of nuclear weapons was because the country feels threatened, and one of the ways to address the threat is to formally end the 1950-53 Korean War with a peace treaty. (Yonhap)