Nuclear war with North Korea not 'likely': Former CIA director Petraeus

Ret. Gen. Petraeus also said U.S. rhetoric on North Korea is "aimed at China."

"All of this is a communications strategy that is trying to make sure that China understands that this administration is in a very different situation than any of its predecessors," he said.

Petraeus said Tillerson’s diplomacy is focused on China's influence with the North Korean regime.

"This is aimed at China," he said. "Secretary Tillerson is undertaking the kind of strategic engagement that is necessary here to build that relationship."

Although Petraeus emphasized the importance of working with China to forestall any need for military conflict with North Korea, he said the U.S. armed services are ready if necessary to take on Kim Jong Un's forces.

"If there is some kind of military engagement, we will be the best prepared we can be. But needless to say, any possible scenario will be ugly," he said.

"The sooner that ISIS can be shown to be a loser is the sooner that it’s no longer effective at recruiting and proselytizing and encouraging, inspiring and so forth, and that is now very much the case," Petraeus said.