Some missiles paraded in North Korea on the weekend may have been fake or empty, but the world's intelligence communities are justifiably taking the weapons on display very seriously, experts say.

Key points: Parade included weapons systems that showed North Korea has second strike capability

Parade included weapons systems that showed North Korea has second strike capability Missiles may have been empty shells with technology stored elsewhere

Missiles may have been empty shells with technology stored elsewhere Parade signals ambitious shift in state's weapons program

As the parade was under way on Saturday, many people watching coverage took to social media to say some missiles were wobbling in the wind and at least one appeared to be bent.

"I suspect they all might be mock-ups aimed to impress the outside world," Lee Il-Woo, a senior analyst at the private Korea Defence Network, said.

However security and international diplomacy expert at RMIT University, Joseph Siracusa, said while some of the weapons could have been fake or simply empty, it was unimportant because experts could identify real weapons systems which showed, for the first time, North Korea had second strike capability — the ability to respond to a major strike on the nation.

Professor Siracusa said second strike capability was something the world's "big boys" possessed.

Sorry, this video has expired Pyongyang puts on show of force as Trump hardens North Korea rhetoric

Euan Graham, the director of the international security program at the Lowy Institute for International Policy, agreed, saying while some of the missiles could have been fake it was ultimately inconsequential.

"Particularly in terms of the canisters in the parade, they are essentially the wrapper in which the missile may or may not be contained, and it doesn't mean that they haven't developed it," he said.

"It is just kind of operational good sense for North Koreans to parade an empty canister. They achieve nothing by filling it with a missile, especially if they are worried about air strikes — it just creates an extra level of complication and risk.

"It may be a bluff or it may be that the missiles are stored separately — the point is it creates the doubt and uncertainty that defence planners will have to take into account."

Both experts said the world's intelligence communities were scouring the footage for information on the regime's weapons capability and plans.

Professor Graham said the parade signalled an obvious ambitious shift in North Korea's weapons program.

"My big takeaway from [the parade] is the emphasis on the very long range, previously unsighted systems is a statement of grand ambition on Kim Jong-un's part that North Korea is not just settling for a minimum deterrent. It wants the Rolls Royce," he said.

He said it showed North Korea's military intentions were more than defensive.

"If it was only that [defensive] then it would be easier to live with, but I see the ambition of North Korea as being more destabilising than that," he said.

"If that's all they wanted to do there's no need to develop ICBMs [intercontinental ballistic missiles] or any of these extraordinarily costly and complex systems — even going for a submarine second strike capability, which for a country that's struggling to compete with Ethiopia in terms of GDP terms is an extraordinary level of perverse ambition."

China telling N Korea to 'get your house in order'

The parade marked the 105th birth anniversary of the country's founding father Kim Il Sung. ( Reuters: Damir Sagolj )

The two experts warned the threat posed by North Korea should not be underestimated.

Professor Siracusa said time was running out for the nation to respond to international demands to stand down before it faced war.

He said if the rogue state's failed missile test on the weekend had been a successful test of an ICBM, the US strike group currently in waters in the region would have responded with force.

He said China did not want North Korea to start a nuclear war on its doorstep and was essentially telling North Korea to "get your house in order".

He said it was extremely telling that China was allowing the US strike group, led by the USS Carl Vinson, in the waters around North Korea and the communist government was also working so closely with the US on how to deal with the rogue state, he said.

Professor Siracusa added if China and the US failed to rein in North Korea, Japan would not hesitate to act with force.

Professor Graham said the risk of immediate conflict was "overblown", but North Korea's power to destabilise the region was not.

"I think that's a more subtle but more realistic risk that you get trouble playing out below the nuclear threshold under that enhanced deterrent that North Korea is acquiring," he said.

"I don't see this now on a short fuse to military confrontation.

"I think the coercive element will be kept there. Really the challenge for the US is to see this through beyond the short term.

"This may be the one time where the US is able to use this peculiar window of [having] rather an unpredictable presidency.

"For all its faults in the policy-making process, it does have that ability to lever off that uncertainty — particularly on China's point to actually keep the pressure up — and even if North Korea doesn't denuclearise, I think a lot can be done to make it more difficult for them to develop [weapons]."