North Korea’s self-proclaimed hydrogen test on Wednesday came somewhat as a surprise to officials in South Korea and surrounding countries who have played down Pyongyang’s stepped-up claims.

Saenuri Party Rep. Lee Cheol-woo, on the parliamentary intelligence committee, told reporters that the nuclear test had no preceding signs, which differed from previous tests.

“Usually a previous announcement and other actions herald the test, but this was not the case,” he said, adding that an analysis of Pyongyang’s post-test announcement is necessary.

The committee, citing sources at the National Intelligence Service, added that Pyongyang did not alert the United States or China. This contrasted with previous cases, in which the communist country had warned China, the U.S. or Russia beforehand.

North Korean leader Kim Jong-un publicly claimed in December that the country was capable of detonating a hydrogen bomb.

Both Seoul and the White House had shown skepticism toward the country completing the development of the hydrogen bomb. Russia echoed their views by saying that the claims were likely a bluff, pointing out that Kim had made false claims before.

Joel Wit, a visiting researcher at Johns Hopkins University, said last month that North Korea could deploy a hydrogen bomb by 2020, although he said that Kim’s claim was “technically unlikely.”

An official from the Defense Ministry, who wished to remained anonymous, had said “there was low possibility” of a nuclear test in the near future for North Korea.

But some experts in academic circles had raised the possibility of an upcoming hydrogen bomb test by the hermit kingdom.

Professor Kim Tae-woo of Konyang University, formerly the head of the Korea Institute for National Unification, said Monday that Pyongyang “may already have the technology to build a H-bomb.”

He pointed out that it took most nuclear nations only five years to jump from the first-generation nuclear bomb to the second-generation hydrogen bomb, adding Kim may be “biding time” for the testing.

But some military officials suspected that Pyongyang may not have used an actual hydrogen bomb in Thursday’s testing. They stressed that the test generated seismic activity of magnitude 4.9 on the Richter scale, which is actually smaller than in the North’s third nuclear test in 2013.

Regardless of the hydrogen bomb’s legitimacy, experts have said the testing will have a resounding impact on the power dynamics of Northeast Asia.

Cheong Seong-chang, a senior fellow at the think tank Sejong Institute, told local media that Pyongyang’s intent is to show off its military prowess by cementing its position, pressuring U.S. to engage in bilateral talks and gaining leverage in negotiations with South Korea.

By Yoon Min-sik (minsikyoon@heraldcorp.com)