Thirteen years ago, North Korea announced its withdrawal from the global nuclear Non-Proliferation Treaty (NPT). Up until the end of 2015, it had since conducted three underground nuclear test blasts, despite strict international sanctions aimed at its nuclear programme and almost universal condemnation of each test.
But last week, it made its most dramatic claim yet - that it had tested a hydrogen bomb. And regardless of whether it was truly an H-bomb (and there is considerable skepticism over whether it was) decision-makers cannot relax - there are still serious long-term implications to what took place this week.
As with all new nuclear weapons possessors, North Korea first developed fission bombs, which are based on the process of heavy nuclei (such as uranium and plutonium) splitting into fragments, releasing large amounts of energy. Fission explosions were the basis of the bombs dropped in 1945 on Hiroshima (a uranium bomb) and Nagasaki (a plutonium bomb).
Hydrogen bombs, also known as thermonuclear weapons, work in two stages: the first detonates a fission bomb to produce energy in sufficient quantities that, when it is then focused on light nuclei, a plasma is created that enables fusion reactions to take place. Hydrogen bombs therefore create far larger explosions than fission bombs.
With this in mind, there is doubt that the device that North Korea tested on 6 January, which had a yield of about 6 kilotons - similar, although perhaps a little higher than previous devices - was really a hydrogen bomb. But even if North Korea has not yet developed a true hydrogen bomb, it seems plausible that the country has developed what is often referred to as a 'boosted fission' weapon, or even an old type of design called a single-stage fission-fusion bomb, both of which can produce a larger yield than traditional fission weapons.
If this is the case, it should be of grave concern to the international community.
The key question is not whether North Korea's technical acumen has advanced to the stage of developing a two-stage thermonuclear bomb, but whether it is capable of creating a nuclear warhead that could be delivered by ballistic missile. If North Korea has developed a boosted fission weapon, this could facilitate progress towards lighter, smaller bombs that could fit on top of a long range missile while still retaining the power to destroy a major city in South Korea, Japan or even, eventually, the United States.
How should the international community respond to this development?
It is certainly time for a new approach and some vigorous action. The parallel process of implementing strict sanctions while sporadically negotiating through the Six Party Talks framework has had little or no impact on North Korea's nuclear programme. But this does not mean that failure is inevitable. One need only look at the case of Iran. Until the E3+3 process, there seemed to be little hope for halting the country's nuclear programme, something that has now been achieved through the 2015 Joint Comprehensive Plan of Action.
Still, the Iran deal could not have been achieved without a number of key features.
First, it required a number of serious so-called Track II processes, which included academic and international NGOs sustaining back channel talks with Iranian counterparts to discuss the possible elements of proposals. Second, the sustained role of both the European Union and the United Nations was critical in creating political legitimacy for a deal. Third, it required time to establish confidence building measures - especially in Iran and the United States - and a focus mainly on the technical aspects rather than the political differences to ease this process. And finally, the Iran deal required a commitment to find agreement between Russia and the United States on the ways forward, even when they did not always fully agree, and when other international crises were creating strains in the relationship.
There are, of course, major differences between Iran and North Korea, not least of which is that Iran had only a potential nuclear weapons programme, and had not yet developed nuclear weapons. Yet this simply underscores the urgency in finding a way to resolve the situation with North Korea, a situation that is far more dangerous.
Ultimately, the Iran deal is an example of the progress that can be achieved when the key international actors put aside other differences to place nuclear non-proliferation and international security as a top priority. In a recent statement, Japan, South Korea and the United States agreed they would work unilaterally if necessary, but it would be far better if the UN Security Council was able to forge a united response in which Russia and China would play major roles.
The Iran deal was significant breakthrough. And we will need exactly the sort of resolve required to achieve it to address the North Korean nuclear challenge if we are to prevent a future nuclear catastrophe.
Patricia Lewis is the Research Director, International Security at Chatham House.
Beyza Unal is a research fellow with the International Security Department at Chatham House.