North Korean leader Kim Jong-un

The new type of intermediate-range ballistic missile launched by North Korea on Sunday is a "game changer", according to analysts, because it uses a solid fuel engine that makes the weapon more stable and reduces the time required to fuel a missile before launch.

The Pukguksong-2 is also road-mobile on tractor-erector-launcher units, analysts point out, all of which means that the weapon is more difficult to detect and neutralise before it is launched.

"The liquid fuel engines that North Korea uses in all its medium- and long-range missiles are dangerous because the fuel is so corrosive and volatile", said Lance Gatling, a defense analyst and president of Tokyo-based Nexial Research Inc.

North Korean leader Kim Jong Un

"It is questionable if they have the capacity to store liquid rocket fuel for long periods and typically they tend to fuel their rockets just before launch", he told The Telegraph.

In October, a TEL unit for a Musudan ballistic missile was badly damaged when the weapon exploded shortly after launch. Five Musudan tests earlier in the year were also judged by South Korean intelligence to have been failures after they blew up in flight.

North Korean state media has claimed that the missiles were deliberately destroyed.

A view of the test-fire of Pukguksong-2

The benefit of a solid-fuel engine - probably utilising ammonium perchlorate - is that the fuel is extremely stable can be easily stored and the weapon is ready to be fired virtually immediately, Mr Gatling said.

"If they have made a solid-fuel engine that works, then that is a great advance", he said.

"It's a game-changer in the sense that a solid fuel rocket can be kept in ambient temperatures before being launched with a very short preparation time".

South Korean intelligence on Monday said that the new missile - fired at 7:55 am local time from Banghyon air base in North Pyongan Province - appears to be employing engine technology used in North Korea's successful submarine-launched missile programme.

The weapon was initially identified as a Rodong missile and then a Musudan, until North Korea released video and still images of the launch on Monday - with state media declaring the weapon to be a "Korean-style, new-type strategic weapon system".

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North Korean leader Kim Jong Un guides the test-fire of Pukguksong-2

The state-run Korean Central News Agency quoted Mr Kim as expressing "great satisfaction over the possession of another powerful nuclear attacks means, which adds to the tremendous might of the country".

Intelligence estimates suggest that the Pukguksong-2 has an operational range of 3,000 km (1,860 miles), which is less than the 3,500 km (2,175 miles) of a Musudan. It is considered likely that now North Korean scientists have perfected solid fuel engine technology, they will seek to apply it to a new generation of missiles with longer ranges.

Yonhap news quoted South Korea intelligence officials as saying that they are unsure whether a nuclear warhead can be fitted to the Pukguksong-2.

Mr Gatling said it is "extremely unlikely" that North Korea has not factored a nuclear capability into the weapon.