North Korea's young leader is more likely to opt for additional rocket launches than pulling out a nuclear test card in the foreseeable future, a renowned U.S. expert said Thursday.

The chances of a nuclear test are "still less than 50-50," Frederick Fleitz, formerly a CIA official, told Yonhap News Agency.

Fleitz worked at the CIA for 19 years, dealing with weapons intelligence, nonproliferation and arms control.

In the early 2000s, he also worked as chief of staff to John Bolton and Robert Joseph, then undersecretaries of state.

Fleitz, now managing editor of the Langley Intelligence Group Network in Washington, was among a small group of experts who predicted another rocket launch by North Korea, not a nuclear weapons experiment, after its failed launch in April last year.

Indeed, Pyongyang fired a long-range rocket again in December, which ended up as a success.

He admitted that it's a tough guessing game again when it comes to North Korea's expected provocative steps down the road,

The secretive communist nation's new leader, Kim Jong-un, has followed some of his father's provocative strategies but also signaled a new approach, Fleitz said.

In that sense, he said, more rocket launches are more likely in that Pyongyang can argue that they are peaceful.

"Also, they can make money. They can win customers. They can sell more missile technology to Iran," he said, adding Pyongyang knows a nuclear test is "extremely provocative."

Meanwhile, a U.S. government official reiterated calls for Pyongyang to refrain from either nuclear or missile tests.

"The United States calls on the DPRK to refrain from additional provocations, including actions that violate its international obligations and run counter to its commitments," the official told Yonhap, requesting anonymity. DPRK is the acronym of North Korea's formal name, the Democratic People's Republic of Korea.

"The DPRK will only achieve true security and prosperity by choosing the path of peace and progress, and by honoring its international commitments and obligations," he added.

He said it's important to send a consistent message, although it may be boring, to North Korea. (Yonhap News)