When North Korea launched its first intercontinental ballistic missile two weeks ago, the fury was immediate.

Seoul called it an "irresponsible provocation" and stepped up live-fire military exercises. Tokyo condemned the "major escalation." Washington threatened to unleash "the full lethal capability of our allied air forces" as U.S. B-1B bombers buzzed the Korean Peninsula.

To many it seemed that only a military response could stop North Korean leader Kim Jong-un from carrying through on his threat to develop a nuclear missile capable of hitting the U.S.

But this week, the sabre rattling turned to sunshine — at least as far as Seoul is concerned.

South Korean President Moon Jae-in has formally offered to launch talks with the North over military and humanitarian issues, a big step toward reviving a so-called "sunshine policy" that stresses negotiation instead of confrontation on the peninsula.

He's even softened his previous position when he said talks would only make sense "when conditions are right."

"Talks and co-operation between the two Koreas to ease tension and bring about peace" are instrumental to solve the impasse now, said South Korean Unification Minister Cho Myoung-Gyon on Monday. The proposal is to meet at the border village of Panmunjom on July 21.

South Korea Koreas Tensions

South Korean soldiers pass military vehicles from the Korean War era at a museum in Seoul on Monday, The country is still officially at war with North Korea. (Ahn Young-joon/Associated Press)

There has been no reply yet from the North. But even if it rejects this offer, Robert Kelly says, Pyongyang would likely be interested in going through the motions. He's a professor of international relations at South Korea's Pusan National University.

"Negotiations make the North Koreans look like an important power," Kelly says. "It looks like a real country, rather than a sort of weird, miscreant portion of South Korea."

Seoul and Pyongyang have not met face to face since 2015 and there hasn't been regular co-operation since 2008.

Overtures dismissed as naive

That year ended a decade of joint initiatives, including an industrial park, tourism projects and family reunification efforts. Many dismissed these as naive overtures by the South that were exploited by the North for economic and political gain, while its weapons program continued.

Conservatives took over in Seoul in 2008, and positions hardened on both sides of the heavily guarded Demilitarized Zone, two Koreas observing an armistice but still technically at war since 1953.

Five underground nuclear explosions and dozens of missile tests later, Pyongyang is closer than most experts predicted to having a weapon that can hit not only the U.S, but Japan and much of the region.

South Korea AP Explains Koreas DMZ

U.S. Vice-President Mike Pence looks at North Korea from Observation Post Ouellette in the Demilitarized Zone, near Panmunjom. The village is the proposed site for the first face to face talks since 2015. (Associated Press)

So why offer to play nice now?

First, Moon's overture is the fulfilment of a campaign promise from his landslide victory two months ago, reflecting a popular sentiment among many South Koreans, especially those on the left. A poll last month found that almost 77 per cent wanted Seoul to return to dialogue with Pyongyang.

'Our previous governments had been confrontational and that didn't work.' — South Korean Jung Mi-ok

Like 39-year-old Jung Mi-ok, they are frustrated with an impasse that's been with them all their lives.

"Our previous governments had been confrontational and that didn't work," she says with a sigh. "I want Moon to restore the sunshine policy and melt this cold war."

For many, a united Korea is still an appealing and realistic goal. Opening talks is seen as a first step.

Catastrophic risks

The second reason for the offer of negotiation is that the other options show no signs of succeeding.

Military strikes have been threatened, but most experts now say such a move is complicated and increasingly risky.

North Korea could already have as many as 20 nuclear weapons, as well as dozens of missiles hidden in underground caves around the country. They are designed to be rolled out and fired within minutes. Hitting all these in a pre-emptive strike would be almost impossible, and any attempt could set off a nuclear war.

Conventional weapons aimed at Seoul pose another catastrophic risk. There are hundreds of artillery pieces within easy range of the South Korean capital, a metropolitan area of 25 million people. If Pyongyang decides to retaliate against a military attack or launch a pre-emptive one the casualties in South Korea would be in the tens or hundreds of thousands.

NORTHKOREA-USA/PENCE-DMZ

North Korean soldiers watch toward the South during Pence's arrival at Panmunjom. (Kim Hong-Ji/Reuters)

Economic sanctions imposed by the United Nations and toughened by the United States have also failed to stop North Korea's weapons program. The best they have done is to slow it down.

Pyongyang has been getting around sanctions largely by continuing to deal with China. The latest figures show a 15 per cent increase in trade in the first half of this year over 2016, even after a Chinese ban on purchases of North Korean coal, the regime's most important money-maker.

And despite international attempts to cut Pyongyang off from the global banking system, it has played an ongoing shell game to get funds and goods through smaller banks and fake companies.

Canada in the line of fire?

One North Korean defector who used to collect money for his bosses in Pyongyang said that over three decades, "we were never in pain or hurting in our trade business because of the sanctions."

Ri Jong-ho now lives in Virginia. He told the Washington Post, "Unless China, Russia and the United States co-operate fully to sanction North Korea, it will be impossible to hurt them."

And that kind of co-operation has been elusive.

Pusan University's Kelly doesn't think the talks will succeed in curbing North Korea, either. "Everybody's skeptical," he says, because "they're never going to give up their nuclear weapons."

Instead, he thinks all countries within reach of Pyongyang should invest in better missile defence systems, like THAAD, the advanced U.S. system recently installed in South Korea.

That means not only countries in the region, such as Japan, but also others in the line of fire: the U.S., and even Canada.