North Korea's high-profile intercontinental ballistic missile tests of 2017 saw Donald Trump and Kim Jong-un trade crude insults and threats of total destruction, with the US President saying he would unleash "fire and fury" on the hermit kingdom.

Key points: The latest missile test may be intended to put pressure on the US ahead of Saturday's talks

The latest missile test may be intended to put pressure on the US ahead of Saturday's talks North Korea is likely to improve its missile technology with every test, analysts say

North Korea is likely to improve its missile technology with every test, analysts say Pyongyang is well known for exporting weapons throughout the world

While the threats felt almost like a distant memory after a year of diplomatic charm offensives by the renegade nuclear state in 2018, Pyongyang has already conducted 11 missile tests this year after talks broke down at the second US-North Korea summit in Hanoi this February.

Most of those tests have involved a short-range ballistic missile or multiple-launch rocket system (MLRS), but Wednesday's submarine-launched ballistic missile (SLBM) — fired just days ahead of nuclear talks with the United States in Sweden on Saturday — is a concerning exception, experts say.

Ankit Panda, author of Kim Jong-un and the Bomb, described the SLBM, the Pukguksong-3, as Pyongyang's longest-range-capable, solid-fuel missile.

"It also marks the first test of a missile unambiguously designed to carry a nuclear payload since the November 28, 2017, test launch of the Hwasong-15 intercontinental-range ballistic missile," he recently wrote.

But despite the significant escalation following a string of missile tests this year, Mr Trump's aggressive rhetoric from 2017 that maintained North Korea's missile launches had to be stopped at all costs has been missing in action this year.

Here's what experts have to say about the situation in North Korea and what it means for the international community in 2019.

Why has North Korea started firing off missiles again after a lull?

The latest missile test could be aimed at putting pressure on the United States. ( KCNA )

North Korea launching the SLBM on Wednesday — just a day after it announced it would resume nuclear talks with the United States — is no coincidence, analysts say.

The working talks would potentially end a months-long stalemate that followed the Hanoi summit.

Former South Korean lieutenant-general In-bum Chun told the ABC he believed North Korea was under the impression that it was in their favour to create "a crisis atmosphere", and "intimidating and extorting" their opponent was part of their negotiating tactic.

"They've been saying unless you give us absolute guarantees, we're not going to denuclearise, and we're not going to be pressured by economic sanctions," he said.

"And just to prove it, they've been firing off these missiles. And just to prove it again, they fired off this SLBM."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 16 seconds 1 m 16 s In-bum Chun said the latest submarine-launched, ballistic-missile test was "very disappointing".

Mr Chun also suggested Pyongyang's strategy deviated from common sense.

"If I'm coming to you with good faith, I don't shoot off missiles, I bring you flowers," he said.

"If they think they can scare or intimidate the United States, I think they're crazy."

Nuclear expert Tong Zhao, from Beijing's Carnegie Tsinghua Centre for Global Policy, said the latest missile test could be aimed at putting pressure on the United States.

"Last year, North Korea was busy implementing its charm offensive to try to persuade the international community to remove the political and economic pressure on the Democratic People's Republic of Korea (DPRK)," he told the ABC.

"But this year, after the failure of the Hanoi summit meeting, North Korea felt that it needed to put some pressure on the United States in order to force Washington to take a softer position in the denuclearisation negotiations."

But the latest missile test may have another purpose as well, according to Zhiqun Zhu, a political science professor at Bucknell University.

"Both Kim Jong-un and Donald Trump are limelight seekers," he told the ABC.

"North Korea has not been in the news for a while, so it's not surprising that Kim is moving again to get the attention."

'How bad can it get?': Kim's reminder Pyongyang has nukes

The Pukguksong-3 has been described as Pyongyang's longest-range-capable, solid-fuel missile. ( AP: Korean Central News Agency/Korea News Service )

Professor Zhu said the latest missile test was also intended to be a reminder that North Korea is "nuclear capable".

"While Trump may continue to brush off such tests as insignificant, the fact is with every test, North Korea is likely to improve its missile technologies," he said.

"This launch below water is apparently harder to detect and leaves a shorter time to respond, so it poses a more serious threat to North Korea's neighbours and the US, and the international community should be concerned."

And while North Korea didn't test any missiles in 2018 — at least none that were reported — Mr Zhao said it appeared Pyongyang had continued the research and development of its missile capabilities over the past 18 months.

"We don't know much about the status of its nuclear development, but there are signs that North Korea has continued producing more fissile materials for the nuclear weapons," he said.

"I think with all the North Korean missile tests, especially the submarine-launched ballistic missile … it's clear that North Korea is not interested in completely giving up its nuclear deterrent capabilities.

"It might be willing to make some limited restraints on its programs, but it has no intentions to completely give them up in the near-term future. I think that should be a concern for the international community."

Both Kim Jong-un and Donald Trump are limelight seekers, Zhiqun Zhu says. ( AP: Susan Walsh )

Mr Zhao added the prospect of achieving a "nuclear-free" DPRK looked "very low", and people should be prepared to deal with this reality.

Mr Chun said it was also important to consider the consequences of a nuclear-armed North Korea.

"Already people are thinking 'Well, the Russians, Chinese and French have nuclear weapons, maybe the Pakistanis have nuclear weapons, [so] maybe North Korea can have nuclear weapons — how bad can it get?"

"But look at North Korea, you think that's a normal country?

"So, I think we need to be very careful in what we say and what we think because once North Korea has nuclear weapons, it's going to be a very dangerous world."

Mr Chun added North Korea was well-known for exporting weapons throughout the world, and sometimes the weapon systems ended up with "non-responsible actors".

"And if you think of all of that, it's bad news for everyone, not just for the Korean Peninsula."

Could a third US-North Korea summit be in the works?

Donald Trump steps from the DMZ into North Korea at Kim Jong-un's invitation. ( ABC News )

North Korea and the US have not had formal negotiations since the second summit in Hanoi ended abruptly without any agreement.

Last month, it was reported Mr Trump had said he would want to know what would result from a third summit before agreeing to hold it.

Mr Zhao said in the best-case scenario, the two sides might be able to reach some preliminary agreement during the working-level negotiations.

"North Korea may be willing to give up its Yongbyon nuclear complex, and that would greatly limit North Korea's capabilities to build more and better nuclear weapons, but it wouldn't eliminate North Korea's existing nuclear capabilities," he said.

"And in return, I think the United States may be willing to first declare an end to the Korean War — that is a low-hanging fruit — and secondly, be willing to improve bilateral political relations with DPRK.

"The United States may [also] be willing to temporarily remove certain economic sanctions from DPRK."

Mr Chun said in order for Pyongyang to denuclearise, Beijing needed to be convinced that it was in China's interest to have a nuclear-free Korean Peninsula.



"Right now, sanctions are not working, and the reason that sanctions aren't working is because China is not enforcing the sanctions as hard as they need to," he said.

"So it ties in with the Chinese involvement, and so that's one thing that must be a precondition to all of this."

Professor Zhu said while it appeared Mr Kim and Mr Trump would both like to strike a deal, many questions remain.

"What kind of deal is the Trump administration prepared for? How far is Trump willing to go?

"What exactly does Kim Jong-un want? Can the US satisfy his demands such as a peace treaty or diplomatic recognition?

"These will be tough issues to discuss during the North Korea-US talks."