A top U.S. official says he hopes a high-level Chinese delegation can successfully persuade North Korea to return to the six party talks aimed at resolving the North Korean nuclear crisis. Meanwhile, in New York, the U.N. Security Council is preparing to vote on a tough resolution aimed at punishing North Korea for conducting missile tests last week.

World condemnation of the North Korean missile tests last week has been distilled into an impending resolution in the U.N. Security Council.

The State Department's Nicholas Burns described the U.N. resolution as "tough", and said one key issue is whether or not it has the support of China, one of the Security Council's five veto-wielding members.

"We do not have assurances right now. We understand the Chinese right now are reflecting on their options," said Burns.

He told the CBS television program, Face the Nation, Beijing is sending senior Chinese officials to North Korea, a development he hopes will produce some results.

"They wanted to see how this [Chinese] delegation could do in Pyongyang, before this vote in the Security Council. So, all of us thought it was best to postpone that vote, until early this week, so that we could see results of the Chinese mission. But we will have to take this one step at a time," continued Burns.

Burns added that, if the Chinese are not successful, Washington is still pushing for the U.N. Security Council to pass a resolution to try to pressure North Korea to return to the negotiating table.

"Well, in the Security Council resolution that is under consideration, it would prohibit any member of the United Nations from engaging in any trade that would in any way benefit North Korea's missile programs or nuclear programs," he noted. "It is an obvious step to take. It would be severely disruptive to what the North Koreans are trying to do. And that is why we are pressing it forward."

Speaking on the same television program, Republican Senator John McCain called U.S. concerns over North Korea "a defining issue." He added that last week's North Korean missile tests help bolster arguments for the United States to strengthen its own military defenses, and help other countries in the region.