The US appealed  to South Korea on Thursday to show restraint as the danger  level from North Korea rises, but again criticised China for  enabling its ally Pyongyang's "reckless behaviour".

The South has vowed to hit back hard against its neighbour  if Pyongyang orders a repeat of last month's attack,  bolstering its defences in the disputed West Sea area and  amending military rules of engagement to permit the use of  fighter jets and bombs.

"I actually believe that because these provocations  continue, and seemingly at a more frequent interval, that the  danger is going up and that steps must be taken to ensure that  they stop," Admiral Mike Mullen, chairman of the US Joint  Chiefs of Staff, told a news conference in Tokyo.

Last month's attack on Yeonpyeong island, the first of its  kind against civilians on South Korean soil since the end of  the 1950-53 war, coupled with the North's revelations of  nuclear advances, have boosted tension on the divided peninsula.     

Washington has repeatedly urged Beijing to rein in  Pyongyang.

"Much of that volatility is owed to the reckless behaviour of the North Korean regime, enabled by their friends in China," Mullen said.

He also said that the United States wants sustainable  military ties with China, instead of on-and-off contact.

At  the same time, Beijing said it had sent General Ma Xiaotian,  deputy chief of general staff of the People's Liberation Army,  to the US for military-to-military talks.

Mullen justified staging joint military exercises with  South Korea off the west coast of the peninsula, saying the  Yellow Sea is free waters where the US military has operated  and will continue to do so.

A US military official said Washington was encouraging Seoul to think strategically and in the long-term rather than  focusing on tit-for-tat retaliation.

"Any actions that are taken -- actions, reactions -- have to be done very carefully to make sure that we don't escalate,  that they are proportional, and at the same time send a very  strong signal that the provocations must cease," Mullen said.

Analysts say Pyongyang will likely stage further, possibly  bigger incidents, in the future to cement a leadership  transition from ailing leader Kim Jong-il to his son. They say  the North, which has a military-first policy, also stages what  they call "provocations" to extract concessions at  multilateral talks.

North disputes demarcation

Earlier on Thursday, North Korea released a report on defending last month's deadly attack on a South Korean island,  accusing Seoul and Washington of "persistently escalating  tension" in disputed seas off its west coast.

The North fired a barrage of artillery shells at  Yeonpyeong, one of five South Korean islands straddling the  contested Northern Limit Line (NLL) sea border, killing four  people, including two civilians.

Pyongyang said it had fired artillery at the island after South Korea had fired into its waters. Seoul said it had only been conducting regular military drills in the area at the time.

South Korea "fired as many as thousands of shells into the territorial waters of the DPRK (North Korea) side", the state  news agency quoted the Secretariat of the Committee for the  Peaceful Reunification of Korea report as saying.

"This reckless act was obviously a deliberate provocation to prompt the DPRK to take a military counter-action," it said.

Pyongyang does not recognise the NLL, arguing that the demarcation was established without its consent after the  1950-1953 Korean war.

There have been several deadly battles in the area over the past decade, and in March a South Korea warship was torpedoed  killing 46 sailors.

"The above-said island is located deep inside the territorial waters of the DPRK side from the maritime  demarcation line," the report said.

"If any live shell firing is conducted from there, shells  are bound to drop inside the territorial waters of the DPRK  side no matter in which direction they are fired because of  these geographical features of the island."
Both Koreas frequently conduct drills in the area.

The statement also said the South had "persistently mocked at the DPRK's sincere efforts to improve the inter-Korean  relations and turned away their faces from them".

The North has said it wants to resume six party nuclear talks, but Washington and Seoul have said they will only  consider a return to the negotiating table when Pyongyang  shows it is sincere about denuclearisation. – Reuters