An expert explains what will happen within minutes of a potential missile launch.
Just over four years ago, the world started to take North Korea more seriously.
While Kim Jong-un was earning his own reputation for being a ruthless world leader, four of his closest comrades were establishing North Korea as a global nuclear power.
Kim Jong-sik, Ri Pyong-chol, Jon Il-ho and JangChang-ha have become known by nicknames such as the "nuclear duo" and the "missile quartet".
(L - R) Kim Jong-sik, Ri Pyong-chol, Kim Jong-un, Jon Il-ho and Jang Chang-ha inspect the test-fire of ballistic missile Pukguksong-2. Photo / AP
Since the North Korean leader came to power in 2011, he has executed 340 people, a recent report claimed.
Of those killed, nearly half were senior officers in his own government and military.
However, those creating the country's nuclear weapons aren't subject to the same level of fear.
Speaking to the New York Times, a senior researcher in South Korea and the head of a database of North Korean scientific publications said Kim was more relaxed with his scientists.
"We have never heard of him killing scientists," Choi Kyun-kyo, the head of NK Tech said.
"He is someone who understands that trial and error are part of doing science."
All of the men in the photograph are being watched by western intelligence agencies, according to Reuters.
Kim Jong-sik was first photographed with his dear leader in February, 2016. His rise through the ranks has been linked to an acceleration of test launches.
Speaking to Fox News earlier this year, director of North Korea Leadership Watch Michael Madden said Jong-sik had been "plucked from obscurity".
His engineering background has turned him into a "key figure" in the North Korean regime.
A man watches a TV news program showing photos published in North Korea's Rodong Sinmun newspaper of North Korea's missile launch. Photo / AP
Ri Pyong-chol is the quartet's highest ranking member.
Speaking to news.com.au, director for centre for performance studies at UCLA Professor Suk-Young Kim described Ri as the political figurehead.
"He was a commander at the North Korean Air Force and in 2014 was transferred to the Department of Military Engineering, which operates under the North Korean Workers' Party."
Ri now serves as the first deputy director of the munitions industry department.
Jon Il-ho is normally described as an official in scientific research and is the third member of the nation's "missile quartet".
Jang Chang-ha, the last man in the photograph, is the president of the Academy of National Defence Science.
When Kim visited his grandfather's mausoleum in July, often considered the most important annual ritual of his regime, these four men were by his side.
Ri Hong-sop, who is not in the Pukguksong-2 launch photograph, is another key player.
He is the director of the country's Nuclear Weapons Institute and has been on the United Nations blacklist since 2009.
The men have even been photographed smoking with Kim, which, according to the New York Times, is often seen as inappropriate in Korean culture to smoke with a father or teacher.
WHERE SCIENCE REIGNS SUPREME
Despite United Nations sanctions prohibiting North Korean students applying scientific lessons to military development, the country has found a way around it.
Instead, students are sent to places like China, India and Germany where they learn the science and bring it back to North Korea.
Then, when they return home, their top science students are pushed into military projects, often only allowed to visit their families and hometowns with government minders.
In Pyongyang, a six-lane avenue called Future Scientists Street runs through the city, replete with apartments for scientists and their families to live in.
A huge, atom-shaped complex towers nearby, an ode to the country's achievements in nuclear science.
North Korea's scientists are also given unprecedented access to the internet, who scour the web for military data, under the watchful eye of security agents.
The scientists are also given better food rations. A welcome change from the near-starvation much of the North Korean military face.
In Pyongyang, a six-lane avenue called Future Scientists Street runs through the city, replete with apartments for scientists and their families to live in. Photo / KCNA
Kim Eun-jung, who escaped to South Korea via China after serving 10 years in the North Korean army, recently told the Times life in the army is miserable.
"Everyone was sick in the army, all the time," she said.
"They took away what should have been the 10 most beautiful years of my life."
Food is also scarce and of a low quality.
Lee Yun-keol, another defector who now runs the North Korean Strategic Information Service Centre in Seoul, said the rogue nation was trying to recruit scientists from the former Soviet Union.
Speaking to the New York Times, Lee said North Korea has offered scientists from the former Soviet Union salaries as high as US$10,000 ($14,300) a month - a small fortune when compared to the typical amount they pay pensioners — around 65USc a month. Workers earn around US$2 to US$3 a month.
