BEIJING - The Democratic People's Republic of Korea (DPRK) vowed on Monday to strengthen its nuclear weaponry as the world intensified pressure on Pyongyang over the sinking of a warship.
Pyongyang's military accused the US of bringing heavy weapons into the border truce village of Panmunjom and warned of "strong military countermeasures".
Tensions have been high on the Korean Peninsula since the Republic of Korea (ROK), citing a multinational investigation, accused its neighbor of sinking its warship Cheonan near the disputed water border in March, and submitted its case to the UN Security Council.
The DPRK, which angrily denies responsibility, has threatened a military response if the UN Security Council takes action over the issue.
"The recent developments have made the DPRK feel more uneasy, which is sure to lead to a furious reaction," said Liu Jiangyong, a professor of Asia-pacific studies at Tsinghua University.
US President Barack Obama said on Sunday the world needs to rally around the ROK to send the DPRK a clear message.
On Sunday, the DPRK rejected a call for a meeting of the commission overseeing the truce and demanded direct military talks with the ROK to discuss the sinking.
"The DPRK is currently seeking to handle the situation in two ways. On one hand, it will show no sign of weakness, and on the other it is seeking negotiations with the ROK," said Liu.
Large-scale, anti-submarine drills were set for earlier this month in the ROK, but were postponed to give the US more time for preparations.
They had been rescheduled for this week, but were delayed again and may take place in July.
"If they insist on holding the drills under the current circumstances, it would only further escalate tensions in the region," said Zhai Dequan, deputy secretary-general of the China Arms Control and Disarmament Association.
"The US and ROK should continue to postpone or cancel the military drills," Zhai said.
Obama said on Sunday he understood Chinese President Hu Jintao's need to show restraint over his neighbor and ally, but "there's a difference between restraint and willful blindness to consistent problems."
Japanese Prime Minister Naoto Kan told reporters on Sunday he has also asked China to issue a "necessary" condemnation of the sinking.
"China proceeds from the perspective of safeguarding peace and stability on the Korean Peninsula in dealing with the Cheonan incident, and we will continue to do so," foreign spokesperson Qin Gang said last week.
Russia has sent a group of experts to the ROK for a separate investigation. Their assessment has yet to be made public.
A Russian Navy source reportedly said the experts had not found convincing evidence of the DPRK's involvement, said the Hindu, the second-largest English daily in India.
US Central Intelligence Agency Director Leon Panetta said on Sunday that DPRK might have torpedoed the ROK warship to bolster the credibility of Kim Jong-il's son as heir apparent.
"Our intelligence shows that at the present time there is a process of succession going on. I think that (the DPRK's accused torpedoing of the ROK warship) could have been part of it, in order to establish credibility for his son," Panetta said.
The official KCNA news agency reported on Saturday that the ruling Workers' Party of Korea will hold an important conference in early September to elect its highest leading party, which was interpreted as a signal Kim might be getting ready to hand over the reins of power to his favored third son, Kim Jong-un.
Agencies contributed to the story.