Read and watch more about North Korea in "March Madness," a VICE News special section on the Hermit Kingdom.

North Korea launched a pair of short-range ballistic missiles into the sea on Thursday, defying UN Security Council resolutions and threatening South Korea for hosting joint military drills with the United States, which Pyongyang believes are a dress rehearsal for an invasion. The latest launch follows North Korea's fourth nuclear test in January, a long-range rocket launch in February, and the recent publication of photos that purportedly showed young leader Kim Jong-un posing with a nuclear warhead.

Given the uneasy state of affairs on the Korean peninsula, it's easy to forget that barely a decade ago, Pyongyang agreed to abandon its pursuit of nuclear weapons altogether. In September 2015, as part of the Six Party Talks with the US, Russia, China, South Korea, and Japan, North Korea reached an agreement to denuclearize in exchange for fuel aid and other incentives.

The success was short-lived. North Korea, which at the time was still under the leadership of Kim Jong-il, conducted its first nuclear test a year later in 2006. It's mostly been downhill ever since, with Pyongyang intermittently conducting more nuclear tests, which are invariably followed by more sanctions by the international community. After the latest nuclear test and rocket launch, the UN enacted what is essentially a blockade that requires inspections of all goods going into or out of North Korea.

To get a better sense of how North Korea's nuclear situation spiraled out of control — and to learn about how the rest of the world could go about prodding the Kim regime to return to the negotiating table — VICE News sat down with Victor Cha, one of the US representatives in the Six Party Talks, and the former director for Asian affairs on the National Security Council under President George W. Bush.

Cha, who is now a senior adviser and the Korea chair at the Center for Strategic and International Studies, was adamant that "the only path to denuclearization is through some form of negotiation," but he fears it might be too late to convince North Korea to give up its nuclear arms.

"As much as we have wanted over the past 25 to 30 years to focus our negotiations on getting them to give up their nuclear weapons, I don't think they're going to give up their nuclear weapons anymore," Cha said. "There may have been a time in the past where they were interested in negotiating them away, but it just seems like we're too far down the road now, and they seem to be very set and very comfortable with their nuclear capabilities."

Watch **North Korea's Nuclear Threat: VICE News Interviews Victor Cha:**

Cha explained that North Korea sees its nuclear weapons as the ultimate deterrent against an invasion by the US and South Korea, its enemies since the Korean War. And Pyongyang doesn't have to go too far back in history to find examples of other repressive regimes that weren't armed with nukes and ended up getting overthrown by the US.

"They have seen what happens to countries that don't have nuclear weapons," he said. "Afghanistan, for example, Iraq — in their minds, these countries are prone to being invaded by the US. So, I think they understand that there's pain that comes with these actions that they take. But, their objectives are longer term, and they're willing to endure that pain, and we have seen throughout history that they really don't care about the affect on their population."

North Korea claims that its most recent nuclear test was of a hydrogen bomb, the most powerful type of nuclear weapon. While experts in the international community are skeptical, Cha said that the West tends to underestimate their capabilities. He gave the example of the November 2014 hack of Sony Pictures Entertainment, which the US has blamed on North Korea. Until then, Pyongyang's cyber warfare capabilities were largely overlooked. Earlier this week, South Korea's spy agency admitted that North Korean hackers had successfully gained access to the phones of around a dozen government officials.

"After Sony, everybody realized they're further along than we think they are," Cha said. "The popular perception is here's this crazy dictator who tries to fire rockets into the air and they just explode on him… and we fall into that," Cha said. "But each time they are successful it's much further than we thought they were, and that's always worrying."

Still, even if North Korea has a hydrogen bomb and the technical know-how to mount that weapon on top of an intercontinental ballistic missile capable of hitting the United States, Cha doesn't expect the Kim regime to follow through on its threats of launching a nuclear attack.

"Even though North Korea, the regime and the leadership, is a little unpredictable, I don't think they're suicidal," Cha said. "I think they understand the basic strategic calculation that if they were to launch something at the United States, Alaska, Hawaii, or the homeland, that essentially, as President Clinton said many years ago, that would mean the end of North Korea as they knew it."

'We have to worry about nuclear proliferation. Whether internationally or not, something leaks out, it could end up in the hands of ISIS for all we know.'

The bigger concern, at least in Cha's eyes, is the possibility that North Korea could sell its nuclear weapons to a group that is even more dangerous and less predictable, such as the Islamic State, also known as ISIS.

"We have to worry about proliferation," Cha said. "That, whether internationally or not, something leaks out, it could end up in the hands of ISIS for all we know. We have to worry about that."

As for the latest round of UN sanctions, which block exports of valuable commodities like coal, and ban imports of everything from airplane fuel to luxury goods like watches, jet skis, and snowmobiles, Cha said the key to enforcement is China. There have been recent reports of North Korean coal shipments being blocked at the Chinese border, and China also barred a North Korean freighter from entering one of its ports.

In previous years, however, Beijing has agreed to enforce sanctions, only to eventually ease up and allow trade with Pyongyang to continue virtually unfettered. Cha noted that after North Korea's first nuclear test in 2006, bilateral trade between China and North Korea actually increased despite the enactment sanctions.

"The dilemma for the United States and the international community is that we've always wanted China to squeeze North Korea longer and harder than they do," Cha said. "And so that will be the test of these new sanctions. We will see for how long and how hard the Chinese are willing to squeeze the North Koreans."

The two countries are ostensibly allies, but Cha explained that they have a complicated relationship. North Korea needs goods and trade with China to keep the Kim regime propped up, while China wants stability on its northeastern border. But there's mutual dislike, and Beijing has recently reprimanded Pyongyang for its nuclear tests.

"I think that the North Koreans don't view the Chinese as close friends and allies," Cha said. "I think they feel like the Chinese treat them with disrespect, that the Chinese treat them like a poor province."

"And it's the same thing for the Chinese," he added. "I think the Chinese despise the North Koreans. I think they feel like, especially this new generation of leadership in China, feel like if there ever is a weight that is tied to their ankles, it's North Korea… I've described it as sort of they're in a mutual hostage relationship. Neither of them can afford to leave the other."

Cha noted that one of Beijing's biggest concerns is avoiding the collapse of the Kim regime, which could send millions of refugees pouring across the border into China's northeastern provinces, where many ethnic Koreans already reside. The biggest threat, Cha posited, is not harsh new sanctions or a coup, but the outbreak of disease.

"North Korea, I think, quite frankly is one pandemic away from collapse, because they do not have the health system to deal with it," Cha said. "And this is very much evident in the way that they respond every time there's an outbreak of something in the area. Whether it's SARS, MERS, the Middle East respiratory syndrome in South Korea, you can see that the North Korean state responds in they go into almost panic mode and try to shut down the country completely."

Cha urged continued diplomacy with North Korea, and said that the latest round of UN sanctions — if properly enforced — could be the best bet to restart the Six Party Talks and reach some sort of agreement to reduce Pyongyang's nuclear threat and ease tensions on the Korean peninsula. It's in everyone's best interest, he said, for that to happen.

"The purpose of this [latest round of sanctions] is not to collapse the regime," Cha said. "The purpose is to get them to come back to the negotiating table."