The key to solving the issue of North Korea's ballistic missile and nuclear programs is in the United States' hands, China's U.N. envoy said on Friday, urging Washington to show "more sincerity and flexibility" if it wants a breakthrough.

"They should come up with more attractive and more practical, more flexible approaches, policies and actions in accommodating concerns" of North Korea, Ambassador Zhang Jun told reporters. "The key in solving this issue is already in the hands of the United States."

He spoke ahead of a closed U.N. Security Council meeting, which was requested by the United States to discuss North Korea's launch of an intermediate-range ballistic missile last Sunday.