Washington must shoulder its responsibility to solve the Korean Peninsula issue and review its policies, observers said.

Their call came as Washington and Tokyo meet this week to discuss Pyongyang's latest nuclear test.

The United States should take the major share of blame for rising tensions on the peninsula, and it is time for Washington to adjust its policies toward the Democratic People's Republic of Korea, said Wang Junsheng, a researcher on East Asian studies with the Chinese Academy of Social Sciences.

Washington's DPRK policy has never been clear since the Cold War ended, Wang said, adding this fuelled Pyongyang's sense of insecurity.

The DPRK conducted a nuclear test on Feb 12 — the third since 2006.

However, Wang added that the test was inappropriate, and given the uncertainty of US policy, Pyongyang should remain calm and observe UN Security Council resolutions rather than increase tension.

Six-Party Talks are the best way to solve the issue and all parties should do their bit, said Liu Jiangyong, a professor of international relations at Tsinghua University.

The House of Rep resentatives passed a resolution on Friday, calling for the US to work with other countries to impose additional sanctions on the DPRK, urging Beijing to pressure Pyongyang to curtail its nuclear programs.

Beijing has said it was "firmly opposed to" and "strongly dissatisfied with" Pyongyang's nuclear test. It has called for negotiations to solve the issue.

Shi Yinhong, a professor of international relations at Renmin University of China, told Xinhua News Agency that the DPRK decided to conduct the nuclear test on the basis of its own interests.

The DPRK is an independent country that decides its own affairs, he said.

The US did not respect the security concerns of the DPRK and that is the reason why the nuclear issue on the Korean Peninsula has not been solved, said Chen Qi, a professor of international affairs at Tsinghua University.

"The core of the nuclear issue is that Pyongyang's security concerns have long been ignored by Washington," Chen said.

The US deployed nuclear weapons in the Republic of Korea during the Cold War. It was not until 1991 that Washington removed them.

Despite the withdrawal, Washington said Seoul is still under the protection of its nuclear umbrella, a policy which US President Barack Obama reiterated after Pyongyang's latest nuclear test.

According to the White House, Obama will meet Japanese Prime Minister Shinzo Abe on Friday, and Pyongyang's nuclear test will feature prominently in the talks.

Obama called the test a "provocation" and said he and Abe agreed to cooperate on measures aimed at impeding the DPRK's nuclear program. He said that the US remains committed to defending Japan, including by nuclear means.

"The current situation in Northeast Asia is imbalanced, with the ROK and Japan sheltered under the US nuclear umbrella," Ruan Zongze, deputy director of the China Institute of International Studies, was quoted by Xinhua as saying.

Meanwhile, US Republicans are calling on the Obama administration to take a tougher stance against Pyongyang.

Sanctions were the main tool of the US, said Wang. But sanctions alone offer no help in solving the issue but deepen hostility between the US and the DPRK, he said.

Tsinghua University's Chen said Washington may not want Pyongyang's nuclear issue to be solved, because it offers an excuse for the US to deploy antimissile systems and hold military drills in the region, which are in line with its military rebalance to East Asia.