Seoul: The largest ever US-Japan war games kicked off on Friday in waters off the tense Korean peninsula as the UN`s atomic watchdog voiced "great concern" about North Korea`s nuclear ambitions.
The manoeuvres in the East China Sea dwarf US-South Korean exercises this week in the Yellow Sea that were meant as a show of force to Pyongyang after its regime launched a deadly artillery strike against South Korea.
In their joint display of military firepower dubbed "Keen Sword", the US and its officially pacifist ally Japan started eight days of drills with 60 warships, 500 aircraft and 44,000 troops in southern Japanese waters.
The long-scheduled drill comes in a year when China has had a bitter maritime territorial row with Japan and quarrelled with Southeast Asian nations over what the regional giant claims are its ancestral waters.
China -- which has resisted calls to publicly condemn its long-time ally North Korea over its artillery attack -- has instead called for negotiations with Pyongyang, saying that to talk is better than to "brandish weapons".
The North`s artillery and rocket attack on Yeonpyeong island on November 23 killed two civilians and two marines and wrecked almost 30 homes. It was the first shelling of a civilian area in the South since the 1950-53 war.
Washington, Tokyo and Seoul have snubbed Beijing`s proposal for six-way talks that would also involve Moscow -- opting instead for their own three-way meeting to be hosted by US Secretary of State Hillary Clinton on Monday.
"We`ll keep a close watch on this meeting," said Chinese Foreign Ministry spokeswoman Jiang Yu.
"As the situation on the Korean peninsula is highly complicated and sensitive, we expect the meeting to ease tensions and promote dialogue, rather than heighten tensions and intensify confrontation."
Hillary said she was discussing with Chinese and Russian officials "how we can work together to try to avoid conflict".
"North Korea poses an immediate threat to the region around it, particularly to South Korea and Japan, and a medium term threat, should it collapse, to China," she added.
The top US diplomat also warned that the hardline regime of Kim Jong-Il "poses a longer term threat to the entire world because of its nuclear programme and its export of weapons around the world".
UN International Atomic Energy Agency chief Yukiya Amano in Vienna earlier expressed "great concern" over reports that the North -- which has twice tested atom bombs -- had built a modern new uranium enrichment plant.
A US scientist who toured the Yongbyon nuclear complex last month called it "stunning" and warned that, although it appeared to be for civilian use, it could make weapons-grade uranium to add to the regime`s plutonium stockpile.
Tensions remained high on both sides of the Demilitarised Zone that has bisected the Korean peninsula since the 1950-53 war ended in a stalemate.
While the South is planning another five days of artillery drills next week, Yonhap news agency said the North has deployed 100 new multiple rocket launchers north of the DMZ, boosting their number to 5,200.
The rockets have an effective range of 60 kilometres (37 miles), meaning they could hit the South Korean capital Seoul.
Defence minister-designate Kim Kwan-Jin said on Friday that South Korea would respond with air strikes to any further attacks. Its artillery response last week was widely criticised at home as feeble.
The South was also debating whether to restart psychological warfare broadcasts into the North from massive arrays of Army-green loudspeakers that it mothballed years ago but set up again after last week`s attacks.
The speakers are designed to blast pro-democracy messages and calls for the overthrow of Kim up to 24 kilometres into the interior of the sealed-off country. Pyongyang has warned it would fire at the speakers.
The military and activists have already used another propaganda weapon, floating balloons with leaflets designed to destabilise the regime, with Kim planning to hand power eventually to his 27-year-old son Jong-Un.
The Korea Herald said that because the regime cannot be expected to give up its military adventurism, promoting regime change was logical.
"Although it is difficult to expect a top-down regime change in the North, there exists the possibility of a bottom-up change, given the growing discontent among North Korean people toward their leaders," it said.
"Sending balloons could be an effective means of achieving this goal."