After spending more than 20 years in the Central Intelligence Agency, Jami Miscik knows a thing or two about foreign relations.

During an interview at Fortune’s Most Powerful Women Summit on Tuesday, she gave a harsh warning to whomever is sworn in as president in January: Don’t underestimate North Korea’s nuclear power.

“North Korea is one of the issues that we aren’t paying enough attention to,” she said. “The president-elect is going to face a problem with North Korea that none of his or her predecessors have faced. It is well on the way to becoming not just a nuclear power, but a power that is able to deliver a nuclear missile.”

North Korea has made strides in both creating and launching missiles: The country has created nuclear weapons using both uranium and plutonium, and perfected many aspects of the missile’s carrier capabilities, among other things, she explained.

Just over the weekend, the U.S. military detected a failed North Korean missile, believed to be a Musadan intermediate-range ballistic missile. And according to Miscik, that missile, although failed, could reach as far as Guam if launched successfully.

 

“Musadan could probably hit Guam, but the next larger rocket would probably be able to hit the U.S.,” she said. “The fact these rocket launches are failing shouldn’t give anyone comfort, because they’re not failing for the same reason—they fail and they fix that thing, and it might fail for another reason, but they’re advancing in terms of their capability.”

However, the true threat to the U.S. will come when North Korea figures out how to successfully launch a missile into space, re-enter the atmosphere, and hit its target, Miscik said, although noting this has yet to happen.

“[A missile] could hit the continental United States at some point,” she said, adding that North Korea’s nuclear capabilities are already a threat to both Japan and neighboring South Korea.

As for a solution, Miscik said that working “very closely and privately with China to understand the dimensions of this problem” would be the most beneficial, suggesting Chinese sanctions could work to stunt North Korea’s growth as a global aggressor.

“I think the Chinese, Americans, South Korea, and Japan need to work together to figure out what to do about North Korea, she said. “You want to shut down their [North Korea’s] ability to carry out their intentions.”

Miscik currently serves as president and vice chairman of the consulting firm Kissinger Associates and is a director at Morgan Stanley.