North Korea has been working on a new ballistic missile submarine, and experts believe its launch may be coming soon, as North Korea recently showed it off.

Were the submarine to achieve true operational capability, it could serve as an alternative strike option and potentially threaten US forces and allies in the region with ballistic missiles tipped with nuclear warheads.

That being said, expert observers believe it will take several years for this "emerging threat" to become a "significant threat."

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North Korea is widely believed to be developing a new ballistic missile submarine that could one day be trouble for US forces and allies in the region, but experts say it may take years to turn this boat into a serious threat.

Last month, North Korean leader Kim Jong Un inspected a "newly built submarine." North Korean media reported that its "operational deployment is near at hand." Observers suspect this is a new ballistic missile submarine, a weapon North Korea has described as "an important component in [the] national defense of our country."

If it eventually works, this kind of submarine would give North Korea an alternative sea-based nuclear strike option to attack countries like South Korea or Japan, as well as US bases. The Kim regime's pursuit of this capability poses another challenge as the Trump administration pushes to dismantle North Korea's nuclear arsenal.

Experts believe the work is underway at a shipyard in Sinpo, a major port city and defense industry hub located on the coast of the East Sea/Sea of Japan where an experimental ballistic missile submarine lives.

Joe Bermudez, one of the authors of a new CSIS Beyond the Parallel report on recent developments at Sinpo, told Insider that North Korea may be close to launching its new submarine, the development of which likely began a few years ago. North Korea already has a submarine-launched ballistic missile, and it has conducted several successful tests, although never aboard a submarine.

The development of this particular submarine has taken longer than some of the other boats in North Korea's arsenal because a ballistic missile submarine is more complicated. But, given North Korea's recent display, it may soon be ready for launch, experts say.

But simply launching a submarine doesn't mean its ready for combat. "Even if launched today the submarine will have to undergo a period of fitting-out, then manufacturer's acceptance trials, KPN acceptance trials, commissioning and finally KPN shake-down cruises before becoming truly operational," Bermudez and Victor Cha, well-known Korea experts explained, in their new CSIS report.

Bermudez suggested that if North Korea launched with the Pukguksong-1, North Korea's only submarine-launched ballistic missile, they might achieve operational capability in a year or two. "If it is with a new system, that could potentially take two to five years," he added.

North Korean leader Kim Jong Un visits a submarine factory KCNA via REUTERS

North Korea has been known to define operational capability a little differently than most countries do, sometimes putting "in service" systems that are actually still in development.

"They could launch this submarine today and within the next six months conduct a test launch from it. That's not operational," Bermudez explained, adding that given North Korea's recent weapons testing, it would not be surprising if they actually took such a step.

Bermudez and Cha characterized North Korea's ballistic submarine program and ballistic missile program as an "emerging threat," explaining in their report that North Korea appears to be "making real progress in developing a second leg of the nuclear triad, bringing them closer to a survivable nuclear force and lessening prospects for full denuclearization," a Trump administration priority that it has struggled to achieve.

Left unchecked, the North Korean program could steadily become a greater challenge. "If they launch, that is a certain level of threat but not overly significant. If they test, that raises the threat. When they finally get to operational, that is a real significant threat," Bermudez told Insider.

If they were to achieve operational capability and if there were an armed conflict, "they could launch at Japan, South Korea, or US bases in the Asia-Pacific region from a direction different from what we have been anticipating and planning for," he explained. "If they were able to achieve a time-on-target for sea- and land-based ballistic missiles, that would further complicate defense."

Read more: Close analysis of Kim Jong Un's new nuclear-missile submarine reveals it's bound for a suicide mission

The new submarine appears crude and is likely noisy, making it easier to detect and eliminate. That being said, its existence raises the threat level as an alternative nuclear weapons delivery platform, and that is especially true if North Korea can find a way to build and field a more than one of them.