Despite escalating rhetoric and North Korea's threat to strike Guam, retired Navy Adm. James Winnefeld Jr. told "CBS This Morning" Wednesday that he doesn't believe the isolated country wants to use nuclear weapons against the U.S.

Winnefeld, who served as the vice chairman of the Joint Chiefs of Staff under President Obama, said North Korea is using the nuclear threat as a "survival mechanism."

"I think we really just need to let them stew in their own juice, leave them alone. They will never use these weapons or give them up as long as we don't provoke them into using them," Winnefeld said.

On Tuesday, President Trump warned that North Korea will be "met with fire and fury" if it continues to ratchet up tensions over its missile and nuclear programs. Winnefeld called the comments "an outburst of sorts" and said he would caution against descending into "angry playground rhetoric."

"I would counsel being circumspect in our rhetoric because, after all, we are the great power here, not North Korea," Winnefeld said.

On Twitter Wednesday morning, Mr. Trump seemed to revisit the topic: "My first order as President was to renovate and modernize our nuclear arsenal. It is now far stronger and more powerful than ever before...."

"I'm encouraged that the president is committed, like previous presidents before him, to modernizing our nuclear arsenal because it is our ultimate deterrent against any kind of threat, including one from North Korea. That modernization has been going on for quite some time," Winnefeld said, referring to the modernization efforts initiated by the Obama administration.

The retired admiral previously served as commander of the North American Aerospace Defense Command, which is charged with preventing air attacks against North America. He said the key focus for the U.S. is maintaining the "twin pillars of deterrence" which include missile defense capabilities.

"We just recently tested for the very first time, our national ballistic missile defense system against a true representative intercontinental ballistic missile threat like the one that North Korea is developing and it performed with flying colors. We also have very capable regional missile defense capabilities and the THAAD missile system which we've installed in South Korea and Guam," Winnefeld said.

While Winnefeld doesn't believe that North Korea will use their weapons, he is concerned about the country selling them instead.

"It is a very big concern and I think that is why the entire international community needs to make a very strong statement to North Korea that not only will you not use these weapons, you will not proliferate them either or there will be very serious consequences," he said.

Asked what he considers the biggest national security threat facing the U.S., Winnefeld said, "I've always worried a lot more about the great powers. In particular, Russia right now. We have a very angry Russia who is expecting to have a very compliant administration and that has blown up in their face with heavy sanctions. Vladimir Putin faces a reelection campaign next spring, so I tend to focus my major attention on that particular threat more than North Korea."