North Korea is ramping up its missile launches and simulated attacks against the South, with experts warning a nuclear test may be imminent.
The isolated communist dynasty under Kim Jong Un recently passed a law enshrining the right to use pre-emptive nuclear strikes and making its status as a nuclear-armed nation "irreversible".
The latest displays of military force come as South Korea is under new leadership, with President Yoon Suk-yeol regarded as taking a more hard-line approach than his predecessor, altering the domestic politics and regional dynamics.
So how worried should we be as tensions increase on the peninsula, and what can we expect next?
What's happened in the past week?
Last Wednesday, North Korea fired 23 missiles — a record number for a single day — with one crossing the maritime border between North and South Korea for the first time.
One missile landed less than 60 kilometres off the coastal South Korean city of Sokcho, triggering a warning for residents on nearby Ullueng island to take cover and prompting South Korea to fire back.
A day later, some residents in Japan were urged to seek shelter after North Korea fired another cluster of missiles, including a suspected failed intercontinental ballistic missile.
The North said its missiles were in response to joint military exercises between South Korea, Japan and the US called "Vigilant Storm".
North Korea described the operation as "provocative" and vowed to "smash the enemies' persistent war hysteria".
Over the weekend, Japan hosted a fleet comprising vessels from 12 nations, including Australia, amid growing tension over North Korea and increasing Chinese pressure over Taiwan.
Is this a cause for concern?
Jean Lee, a policy analyst at the Wilson Center and co-host of the Lazarus Heist podcast, said the pace of North Korea's missile tests was "unprecedented".
"Kim Jong Un is on a mission to expand and diversify his weapons arsenal. And to do that, he needs to test the weapons to perfect and prove their capability," she said.
"We should be worried about the ramp-up of testing. Each test gets North Korea closer to adding to an already-threatening arsenal.
"And every test runs the risk of provoking a conflict in a tense region."
North Korea expert Seong-Chang Choeng told French news service AFP that Pyongyang's missile tests were "the most aggressive and threatening armed demonstration against the South since 2010".
Ms Lee said the fact one missile landed not far from South Korea's shores and sparked a retaliation from Seoul also reminded her of tensions in 2010.
Twelve years ago, South Korea conducted live-fire exercises and North Korea shelled a frontline South Korean island, with those hostilities killing four people.
Why now?
The immediate trigger appears to be the joint military exercises.
However, Jay Song, an expert in Korean Studies at the University of Melbourne's Asia Institute, said it could be a build-up to a new nuclear test.
The last time North Korea tested a nuclear bomb was in 2017.
From a technological and scientific perspective, the time for the North to test its nuclear weaponry again appears close.
"They already have done six nuclear tests, and the next one is imminent," she said.
She said another factor was the change in South Korea's leadership.
Stephen Nagy, a senior associate professor at Tokyo's International Christian University, pointed out Pyongyang's missiles paused during the Chinese Communist Party's Congress, but restarted in the lead-up to the US midterm elections.
"This shows they're deferring to China in efforts for some support, and they're trying to provoke the United States in many ways" in a bid to force the US to the table to resolve complicated diplomatic relations, he said.
Professor Song said the first and last chance for doing a big deal with the US reached a "tipping point" at the Hanoi Summit in 2018, but it was cut short and the door on that possibility closed.
"They're not going to go back to the negotiating table," she said.
"Kim Jong Un is never going to give up his nuclear ambition. He's already declared that — it's in the law.
"North Korea's survival mentality is that they have to really look after themselves, self-defence, and the only way to do that is to develop nuclear weapons."
Some analysts suggest North Korea's playbook has been to ratchet up provocations to get US attention, then negotiate.
But with Russia's war on Ukraine, China's tensions with Taiwan and global economic strife, getting the world's attention could be a challenge.
Professor Song said even with the latest barrage of missiles, there was a perception that this was just common practice for the North.
Meanwhile, South Koreans have been focused on a period of national mourning since the Halloween crush tragedy in Seoul.
"This time it's serious, not because of North Korea's changed position towards South Korea and the US, but because of South Korea's changed position towards North Korea," she said.
Will South Korea go nuclear?
South Korea's former president, Moon Jae-in, who was born to North Korean refugee parents, had a policy of peace, prosperity and dialogue when it came to North Korea.
But his successor, conservative Yoon Suk-yeol, leads a more hawkish administration when it comes to the country's northern neighbour, according to Professor Song.
She said the climate in South Korea could become more unstable, and right-wing and even centrist politicians were voicing support for the idea that South Korea should arm itself with nuclear weapons.
"[This is a] really, really worrisome trend and total change from the previous administration … [which was going] nuclear free, even in terms of the energy sources there," she said.
Writing for The Diplomat last month, Dr Choeng said the significant escalation in threats from Pyongyang demonstrated the need to consider arming South Korea with nuclear weaponry, which he argued would deter the North's threats and spare nuclear war.
Professor Song said North Korea was "gambling big", and if Mr Kim deployed nuclear or even conventional weapons in a direct attack, he risked engaging the world's most powerful military in the US.
"If they attack South Korea or Japan, it's the end of their regime," she said.
She and Professor Nagy said North Korea had refined its nuclear capabilities and wanted to test and prove its delivery methods.
Professor Nagy said there was potential for collateral damage in testing and it could be highly destabilising for the region, which could spiral into conflict.
With a military hotline between the two nations cut off, Professor Song said it was vital to open channels of communication to avoid critical miscalculations, while Ms Lee said the next steps were a delicate balancing act.
"South Korea and the United States now face the challenge of demonstrating strength without allowing the tensions to escalate," she said.
Professor Song added it was no longer a question of the North's capabilities, but managing its motivations.
"When it comes to nuclear war, the accuracy doesn't really matter," Professor Song said.
"If they hit anywhere, even in the sea, the outcome would be devastating … millions of people will die, either on the Korean peninsula or somewhere in the Pacific.
"As a South Korea citizen, I have family here in South Korea. I do really have a real concern."
ABC/wires
