 -- This week's long-range missile test by North Korea marks a distinct, if unsteady, advance in its quest to develop the capability to hit the U.S. mainland, according to two experts.

The distance this missile traveled confirms that North Korea is "no longer just a regional problem. This is a U.S. problem," ABC News aviation consultant Steve Ganyard, a retired Marine Corps colonel, said.

"This is the first time, if the analysis is correct, that we're seeing a North Korean weapon that can hit the United States. Not the mainland, but Alaska is very much part of the United States, and this is a very worrying development," he said on "Good Morning America" today.

Ganyard previously said, "The North Koreans launched this missile almost straight up ... because they didn't want to overfly Japan or Russia."

"The missile itself reached an apex of almost 1,700 miles, which means, had it been on a max-range trajectory, it could have reached Anchorage and wouldn't have been far from reaching Seattle," he said Tuesday on ABC News' "World News Tonight."

Scott Snyder, a senior fellow for Korea studies at the Council on Foreign Relations, said that while the latest test clarified North Korea's ability to fire missiles longer distances, a number of key questions remain.

"There's still a debate whether or not North Korea has been able to make a nuclear weapon small enough to put on the head of the weapon to deliver it, and there's still a debate whether or not North Korea ... has developed re-entry technology," he said.

Such technology would allow a missile to leave Earth's atmosphere and return without burning up, Snyder said.

"The North Koreans are claiming that they have achieved some of those technologies, but it has not yet been definitively proven, and so as a result, there's a little bit of confusion and ambiguity," Snyder said.

"We know they're working on it, so it's really a matter of time before they develop those technologies," he said. "It's not good news."

On the other side, the United States has been working to perfect its system designed to counter North Korea's long-range missile threat.

But that system still needs work, according to Ganyard.

"The U.S. has been developing a ground-based interceptor system that's designed to knock down incoming North Korean missiles, but it's very complex science," he said on "World News Tonight."

"It's very much like hitting a bullet with a bullet, and although the most recent test was successful, the system itself is still only barely over 50 percent reliable," Ganyard said.