"In order to deal with that, you have to change the Chinese calculus, and I think that's what the administration's trying to do. They've worried most about the collapse of the regime, and their long border and instability on their border, Rice said.

"But you have to say to them, even if you have to take very tough steps that might ultimately collapse the regime, you have to take steps because we will if you don't. And I think that's the message that you're starting to see," she said.

Rice said North Korean leader Kim Jong-un is "reckless, maybe even a bit unstable."

Referring to the prospect of the communist nation perfecting capabilities to deliver nuclear weapons on an ICBM, Rice said: "That cannot be countenanced by any American president. I don't care who's in the White House." (Yonhap)