North Korea launched a ballistic missile from a submarine this week.

Or did it?

There are conflicting reports about Wednesday’s launch. While there appears to have been a test of a Pukguksong-3 submarine-launched ballistic missile (SLBM), it’s unclear whether it was fired from an underwater submarine or just some kind of platform.

“The missile, believed to be a type of Pukkuksong, a North Korean SLBM, was fired from off the east coast near Wonsan in an easterly direction at 7:11 a.m. and flew around 280 miles at a maximum altitude of about 565 miles,” said American news agency UPI, citing South Korea’s Joint Chiefs of Staff.

“The high altitude means the missile was fired at a high angle, and if it had been fired at a normal angle, it would have flown a much longer distance.”

However, Fox News is reporting that unidentified American sources believe the missile was fired from a surface barge or an underwater platform. That would be a much less technically demanding achievement than launching a missile from a submarine beneath the waves.

For its part, North Korea’s Korea Central News Agency merely reported that the missile was fired in “vertical mode,” and that “the test-firing scientifically and technically confirmed the key tactical and technical indexes of the newly-designed ballistic missile and had no adverse impact on the security of neighboring countries.”

Yet another North Korean missile launch is almost a yawner. What’s more troubling is that the missile landed in Japanese waters.

Japanese Defense Minister Taro Kono announced that the missile landed Japan’s Exclusive Economic Zone waters “about 350 kilometers [270 miles] north of Dogo Island, Shimane Prefecture, at around 7:27 a.m. after flying 450 [280 miles] kilometers at an altitude of up to 900 kilometers [559 miles],” according to the Japan Times. “Earlier, the Defense Ministry had said North Korea fired two projectiles separately, but Kono said Tokyo now believed a part of the missile fell away and landed elsewhere in the sea.”

Japanese and Western analysts are taking this as Pyongyang’s signal that despite Japan acquiring the U.S. Aegis Ashore ballistic missile defense system, Japanese territory is still vulnerable to North Korean missiles.

A deeper concern with North Korean SLBMs is their relative invulnerability. North Korea’s land-based ballistic missiles, armed with nuclear warheads, are theoretically vulnerable to a first strike by America or South Korea. But submarines, even less sophisticated North Korean models, are much harder to detect. That’s one reason why Britain, France – and possibly Israel – maintain nuclear-armed missile submarines at sea.

Wednesday’s launch marks the first North Korean SLBM test since 2016, when a Pukguksong-1 missile flew 310 miles. Then came the Pukguksong-2, a land-based variant. The Pukgukson-3 may be a switch to a sub-based model.

Either way, an operational North Korean SLBM – or even just the threat of one – is the stuff of nightmares for American, South Korean and Japanese planners. It would make a preemptive strike against North Korea’s nuclear forces much more difficult. It would make a North Korean first strike, from an undetected submarine lurking close to the target nation’s coast, that much more difficult to intercept.

Which is exactly what North Korea wants the world to be afraid of.

Michael Peck is a contributing writer for the National Interest. He can be found on Twitter and Facebook.

Image: Reuters.