Working with China to solve the threat posed by North Korea would be a key priority if Democratic front-runner Hillary Clinton becomes the next president of the United States, her senior policy adviser said recently.

"This is a paramount security challenge for the United States," Jake Sullivan said at a recent Asia Society gathering where he outlined the policy objectives that could take shape. "It will have to be right at the top of the agenda for the next president to deal with."

He added, "There is a possibility for the United States and China to cooperate on the North Korea issue effectively."