North Korea's recent test of a submarine-launched ballistic missile was probably genuine but almost certainly exaggerated, and did not present the imminent threat promoted by Pyongyang, weapons experts and analysts said Thursday.

Reaffirming suspicions that last Friday's exercise was an "ejection" test rather than a full-scale test, the experts said the North was still likely in the early stages of developing a credible SLBM capability.

"Earlier assessments that ... North Korea possesses an emerging regional seaborne ballistic missile threat rather than an imminent threat, and that it does not represent an emerging intercontinental threat, remain valid," said Joseph Bermudez, a chief analytical officer at US-based AllSource Analysis.

Writing on the closely-watched North Korea-watching website, 38North, Bermudez said the SLBM tested last week was probably not "submarine-launched" at all, despite Pyongyang's claims to the contrary.

Instead it was likely fired from a submerged barge that analysts had seen in satellite pictures of the North's Sinpo South Naval Shipyard as far back as October.

And it was probably an "ejection test" in which the missile is launched underwater, breaks the surface and then falls back after a few seconds of partial fuel burn.

"This is a reasonable assessment," Bermudez said, arguing that a full scale flight test, or a launch from an actual submarine would be at the "uppermost limits" of the North's capabilities.

Jeffrey Lewis, an arms expert at the California-based Monterey Institute of International Studies, echoed Bermudez's assessment, but stressed that it did not mean last week's test was a fake.

"This is a normal test to conduct in the early stages of an SLBM program," Lewis said, adding that it represented a "real milestone" -- even if the North had exaggerated its sophistication.

"North Korea has been developing this capability for some time and the recent test is yet another step in that direction," Lewis said.

Given that Kim Jong-Un is closely associated with the program, Lewis suggested the North could move ahead quickly, and even conduct a full flight test later this year.

But several flight tests would normally be required, and there was still the matter of launching the missile from an actual submarine, leaving the prospect of a credible SLBM deployment years away.