After a flurry of launches this year that have alarmed the international community because they appear to significantly extend the range that North Korea's missiles could travel, the "cheap" Scud fired on Monday travelled just 450 kilometres.

But North Korean missile watchers believe the regime's latest launch could be an attempt to perfect a guided-missile system, which, if combined with the longer range missiles capable of flying 4500 kilometres, could allow North Korea to conduct precise attacks against military targets.

This theory appeared to be confirmed on Tuesday, as North Korean media reported its leader Kim Jong-un had watched the test "through a precision control guidance system" a day earlier.

The test was to "verify the technological indices of the new-type precision guided ballistic rocket capable of making ultra-precision strike on the enemies' objects at any area", it claimed.

North Korean news agency KCNA said the latest missile "correctly hit a planned target point with deviation of seven metres".

John Schilling, a missile analyst at Johns Hopkins University's 38North centre, wrote last week that North Korea had made the "extraordinary claim" from its previous medium-range ballistic missile launch that the KN-15 had precision guidance capability.

To back its boast, North Korea had publicly released video transmitted from the KN-15 to receiving stations during its flight, showing images taken from above the Earth as the missile re-entered the atmosphere.

Schilling was sceptical, because he said the re-entry vehicle for the KN-15 did not appear to have thrusters, fins or any other control mechanism.

But he noted that North Korea in the past had twice tested a manouvreing re-entry vehicle (MaRV) with steering fins mounted on an old-style Scud missile.

"It is quite possible they are doing most of the testing using cheap, reliable Scud missiles," he wrote. He said it could take a year to perfect.