The United States has many rockets capable of intercepting another rocket fired toward the country, and many nuclear weapons that could retaliate.
Dr. Robert Carnesale teaches at UCLA. The national security expert spent many years working on international strategic arms limitation talks.
"They might be able to reach the mainland, even within five years," he said. "There's a big difference between that and reaching the mainland with a nuclear weapon, and that's probably way off before they can do that."
Carnesale says the North Koreans are probably trying to get the world's attention and they've been successful.
Symbolically their missile launch sends a message to the United States, China, South Korea and the rest of the world that they can be a force to be reckoned with.
But while it worries Pentagon planners, the missiles in the Chinese arsenal now could be intercepted by U.S. missiles.
"It wouldn't be effective against a missile force as large as the Russians or the Chinese, but if you are talking about one two or three missiles, or five, it's quiet possible we could intercept that successfully," said Carnesale.
With a successful launch, North Korea has shown the world that it is on the way toward developing a missile that could cover thousands of miles and land in the United States.