Seoul: The United States and South Korea announced on Tuesday the start of large-scale military exercises next weekend in a show of force meant to convince North Korea to curb its "aggressive behavior."
The drills are the first overt military response to the March attack on the Cheonan warship that killed 46 South Korean sailors and heightened tensions on the peninsula.
China, North Korea`s only powerful ally, has condemned the planned drills and launched its own naval exercises off its eastern coast.
"These defensive, combined exercises are designed to send a clear message to North Korea that its aggressive behavior must stop," visiting US Defense Secretary Robert Gates said in a joint statement with his South Korean counterpart.
Gates will be joined in Seoul on Wednesday by Secretary of State Hillary Clinton. The two will visit the heavily defended Demilitarized Zone (DMZ) border that has divided the peninsula since the 1950-53 Korean War for which there is still no formal peace treaty.
North Korea denies responsibility for the sinking and a UN statement earlier this month condemned the attack but, in deference to China, avoided any mention of Pyongyang.
North Korea has recently signaled it wants a return to talks with regional powers on its nuclear weapons programme.
Analysts say Washington and Seoul are reluctant to head back into the nuclear talks, which the ostracized North has previously used to extract benefits from the international community while still pressing ahead with efforts to develop a nuclear arsenal.
But they may have little choice with Washington nervous about North Korea`s potential to export atomic weapons, while South Korea`s leaders do not want to be seen as completely turning their back on their neighbor.
Drills anger China
China, which suspended military ties with the United States earlier this year over planned US arms sales to Taiwan, voiced suspicion about the drills due to take place over the coming months in the Sea of Japan and the Yellow Sea.
Gates dismissed any Chinese concerns, saying the drills due to begin on July 25 were routine and in international waters.
"There is nothing provocative about them at all," he said.
But China showed off its growing military might with naval drills of its own, with state TV images on Tuesday showing recent maneuvers by its East Sea Fleet in the waters between its mainland and the Korean peninsula.
South Korean Foreign Minister Yu Myung-hwan, speaking ahead of the talks in Seoul, said the United States was considering additional sanctions against the North in response to the sinking of the Cheonan warship.
Gates, without commenting on Yu`s remarks, said North Korea had already been extensively punished by sanctions.
"I think North Korea first of all is about as isolated as a country can get, in terms of the number of UN sanctions that have been voted against them," he told reporters at a US military base just south of the DMZ.
But Gates acknowledged there was no quick fix to relations with Pyongyang.
"This is an ongoing challenge that has to be managed over a period of years. And I think that the pressures continue to slowly build on the North," he said.
Admiral Robert Willard, who as head of US Pacific Command oversees the US military`s activities in the region, called on China to use its influence with North Korea.
"If I have a concern vis-a-vis China, it`s that China exert itself to influence Pyongyang to see that incidents like the Cheonan don`t occur in the future," Willard told reporters.
"They clearly have a strong relationship with North Korea, and we would like very much to see them exert the influence to see that a Cheonan never happens again."