"And I reiterate again the United States will do what is necessary to defend ourselves and defend our allies, Korea and Japan," Kerry added. "We are fully prepared and capable of doing so, and I think the DPRK understands that."
The North has conducted three nuclear bomb tests, the most recent in February. It has said that its nuclear weapons are a deterrent that are no longer up for negotiation.
Carlin said North Korea's longer-range missiles may not be ready to be used for three to four years, and its nuclear program is a "low-level threat" at this point. He said Washington's most recent moves could be caused by it seeing some sort of movement around North Korean missile facilities, or it could be "misreading and over-reading North Korean propaganda but fulfilling their obligation to be on guard and prepared."
"We're going to get out of this particular crisis, it seems to me, without anything really blowing up," Carlin said. "But down the road, things are going to get more serious."
"What we should be looking at, really, is the decisions and the policies and the approach that we're going to have to take over the next four or five years to deal with these things," he added. "Because for the last five years, we really didn't do a very good job of doing that."