U.S. Assistant Secretary of State Christopher Hill speaks to the press upon his arrival at Beijing's International airport, Sept. 5, 2006

Envoy Christopher Hill is in China for talks with Chinese officials on how to implement a U.N. Security Council resolution meant to stop North Korea from carrying further missile tests.  There is mounting concern in the region about possible plans by North Korea to test a nuclear device.

Assistant Secretary of State Christopher Hill arrived in Beijing expressing frustration over what he said is North Korea's lack of interest in returning to six-nation negotiations.

With the negotiations stalled now for nearly a year, the next option is for the United States and its partners in the talks to implement a U.N. Security Council resolution passed nearly two months ago in response to the North's test-firing of several missiles in the Pacific.

Hill, who earlier stopped in Japan, said he is telling his Chinese counterparts it is time to find concrete ways to put the resolution into action.

He said he sees signs the Chinese, North Korea's traditional allies, are growing equally frustrated with what the North - known officially as the Democratic People's Republic of Korea, or DPRK - has been doing.

"Obviously their relations with the DPRK have undergone some evolution in recent weeks due to the DPRK's decision to go ahead with these missile launches and behavior that I do not think any of us, including the Chinese, were very pleased about," Hill says.

There is a renewed sense of urgency - especially among the United States, Japan, and China - to act as intelligence sources point to signs that North Korea may be preparing to carry out an underground nuclear explosion.

Washington and others have in the past called on China - the chief supplier of food and fuel to North Korea - to use its leverage to get Pyongyang back to the negotiations table.  But Hill said what is important is for all sides to work in tandem.

"I am not here to pressure anybody," he said.  "Obviously, we need to talk about how we are going to implement the resolution and get on with making sure that a resolution like that - which was passed unanimously in the security council - is in fact a resolution that is properly implemented." 

The resolution passed by the Security Council - including China - calls for member states to prevent the transfer of missile and missile-related items, materials, money, and technology that North Korea would use to develop missiles or weapons of mass destruction.

North Korea claims to be developing a nuclear arsenal - in violation of its international agreements - as a means to defend itself from an attack by the United States.  Washington has said it has no plans to launch a strike against the North.