North Korea's pledge not to use nuclear weapons unless threatened by "hostile forces" and to boost global denuclearization, which is based on the acknowledgment of it being a nuclear state, might pose a greater security risk to Northeast Asian countries, observers said.

North Korea "will not use a nuclear weapon unless its sovereignty is encroached upon by any hostile forces with nukes," North Korean leader Kim Jong-un declared at the seventh congress of the Workers' Party of Korea (WPK) on Saturday, the Korean Central News Agency (KCNA) reported.

The young leader added that North Korea "will faithfully fulfill its obligations toward non-proliferation and strive for global denuclearization."

Kim's remarks were downplayed by a senior South Korean official, who told the Yonhap News Agency that there was no "positive message" from Kim's statement. "What the North meant by global denuclearization is it would abandon its nuclear arms when the entire world gives up nuclear weapons," the official said.

However, the "global denuclearization" mentioned by Kim, which was based on North Korea's admission that it possesses nuclear weapons, completely goes against the proposed denuclearization efforts in the Six-Party Talks, Dong Xiangrong, a research fellow at the Chinese Academy of Social Sciences, told the Global Times.

Dong added that Northeast Asia countries and world powers might face severe security challenges, such as a nuclear leak, nuclear accident, or the proliferation of nuclear materials and techniques in the region.

What North Korea wants most is to become a nuclear state and to join the Treaty on the Non-Proliferation of Nuclear Weapons, Lü Chao, a research fellow at the Liaoning Academy of Social Sciences, told the Global Times on Sunday.

"Kim's remarks showed that recent sanctions have been effective, but Pyongyang will not give up its nuclear capabilities completely due to the sanctions. But we should persuade the North to go back to the negotiating table, but not press too hard with military force,"Lü said.

North Korean state TV on Sunday began airing the work report of the WPK Central Committee delivered by Kim, which highlighted North Korea's progress on nuclear weapons.

"Possessing nuclear weapons gives us the greatest happiness," a guide at the former residence of Kim Il-sung surnamed Choi told the Global Times.

Choi added that the North Korean people are very passionate about peace, and developing nuclear weapons is needed against threats from the US and South Korea.

Separately, Kim also laid out a 5-year strategy (2016-20) for economic growth, with special attention to easing a power shortage.

Several North Koreans reached by the Global Times said that they prefer to live in bungalows instead of high-risers, as some tall buildings in Pyongyang remain without power.