The United States and South Korea began naval exercises off the west coast of the peninsula Sunday to send a clear message to North Korea that its aggressive actions must stop.

The drills in the Yellow Sea have infuriated the communist country which warned of unpredictable consequences if the United States sends an aircraft carrier to its waters.

On Sunday, North Korea's official Korean Central News Agency warned, "The DPRK (Democratic People's Republic of Korea) will deal a merciless military counter-attack at any provocative act of intruding into its territorial waters in the future."

China has called for an emergency meeting of the six countries involved in talks about the North's nuclear disarmament. But South Korean President Lee Myung-bak said he was not interested in resuming the six-party talks immediately, according to South Korean news agency Yonhap.

The head of the World Council of Churches has urged the two Koreas to refrain from taking any action that would exacerbate tensions and to get back to negotiations.

"The World Council of Churches’ unequivocal position has been that the use of force and military power will not resolve the problems that deprive the Korean people’s aspiration for peace and reconciliation," said WCC General Secretary the Rev. Dr. Olav Fykse Tveit.

"We call for the governments of North and South Korea to demonstrate the genuine will to return to peace negotiations that will lead to peaceful co-existence and mutual respect, and to engage in a new process of confidence-building measures at the earliest possible date."

The WCC is an ecumenical fellowship and has member churches in South Korea. During the past several decades, the WCC has been engaged in peace and reconciliation efforts on the Korean peninsula.

Tensions heightened on the peninsula on Tuesday when North Korea shelled Yeonpyeong Island, killing two South Korean marines, two civilians and injuring more than a dozen people.

It was the first direct artillery attack on South Korean territory since the 1953 Korean War Armistice Agreement.

North Korea claimed that it was acting in defense in response to South Korea's military exercise that resulted in shells landing in the North's waters.

In a statement Friday, North Korea's news agency said that its "temperament" is to "resolutely counter confrontation with confrontation and war with war".

Amid high tensions, human rights watchdog Open Doors called for prayers as North Korea is known for its unpredictability.

"Its leaders have done everything they could to create a crisis on the Korean peninsula," said Open Doors. "Its army torpedoed and sank a South Korean navy vessel earlier this year.

"Last Sunday it became known that North Korea opened new facilities to enrich uranium. When that didn’t have the desired effect and South Korea continued to perform military exercises, North Korea attacked the island of Yeonpyeong on Tuesday."

The watchdog, which considers North Korea to be the worst persecutor of Christians in the world, contends that the communist country is trying to distract the international community from addressing its human rights and food crises.

All citizens are forced to adhere to a personality cult revolving around the worship of the current dictator and his deceased father. No other religious beliefs are allowed in the country. The possession of a Bible can get an entire family killed or sent to a prison camp.

Open Doors reports that between 50,000 and 70,000 Christians are in labour camps because of their faith. Hundreds of thousands, meanwhile, are in political camps, prisons and re-education camps.