Wang Yi, a vice foreign minister who was China's chief delegate at the negotiations told the New York Times "America's policy toward (North Korea) -- that is the main problem we are facing."
The remark may reflect frustration that the United States offered no concessions to North Korea during the talks, which were organized after extensive diplomacy by Chinese officials.
The Bush administration has maintained that North Korea must dismantle its nuclear program before discussions can begin on any benefits it might receive for doing so. North Korea says it is willing to give up its nuclear program, but only if the United States offers a non-aggression treaty first.
Wang suggested the next round should focus on forcing the United States to elaborate on its verbal commitment to consider North Korea's security concerns.