hankyoreh

Feb. 12. (by Shin So-young

By Kim Kyu-won and Ha Eo-young, staff reporters

Following North Korea’s announcement that it used a “smaller and lighter” nuclear bomb in its third nuclear test, which took place on Feb. 12, the next question is whether Pyongyang can develop an intercontinental ballistic missile (ICBM). Since this is a problem that is directly connected with a threat to the continental US, the US is expected to pay close attention to developments in North Korea.

With its emphasis on “smaller and lighter” in a report by the Korean Central News Agency (KCNA) just after the nuclear test was carried out, North Korea officially announced that they are focusing on developing an ICMB. ICBMs have a range of 5,500km or more and are typically used to deliver nuclear warheads.

At present, if North Korea is to develop ICBMs, there are two problems that it must resolve. The first of these is making the nuclear payload small and light enough to be loaded onto a missile. The second is upgrading its long-range rocket with the technology to leave and then reenter the earth’s atmosphere. It will probably take 4 to 5 more years for the North to develop these two additional forms of technology, military experts say.

Assuming that the warhead is being developed for use with a Scud B missile, the nuclear device first of all must weigh no more than 1,000kg with a maximum diameter of 90cm. This is what is meant by making a smaller, lighter nuclear device. Nuclear warheads that have actually been loaded on missiles are smaller than that, ranging from 110kg (US) to 600kg (China). Generally speaking, when nuclear powers hold their first nuclear test, the nuclear device weighs from 1,300kg-2,200kg. Estimates suggest that the weight of North Korea’s device was in that range.

Dr. Siegfried S. Hecker, a nuclear physicist who has visited North Korea on several occasions, concurs with these assessments. On a visit to South Korea on Feb. 5, he said, “The main purpose for North Korea’s nuclear test is to make a smaller, lighter device.”

It is yet to be confirmed whether North Korea succeeded at developing a smaller and lighter bomb through the third test, as they claimed, and whether they used a nuclear device that was lighter than 1,000kg and less than 90cm in diameter. However, for now, the South Korean Ministry of National Defense and various experts are presuming that the test was conducted with that objective in mind.

“At present, we have no information to confirm whether the North succeeded at making a smaller device,” said Hwang Il-soon, a professor of nuclear engineering at Seoul University. “That said, it can be safely assumed that they have made progress from the time of the first and second tests.”

On Feb. 6, Jung Seung-jo, chairman of the South Korean Joint Chiefs of Staff, addressed a meeting of the National Defense Committee at the National Assembly, saying, “Since it typically takes four years after a nuclear test for the device to be loaded on a missile, the North has probably made considerable progress in creating a smaller nuclear device.”

The second key question is whether North Korea has improved its long-range missile technology enough to make an ICBM. In Feb. 2012, after North Korea used the launch of the Unha-3 long-range rocket to put the Kwangmyongsong-3 satellite into orbit, the general assessment was that the country had reached the first stage in the development of ICBMs. This is because, theoretically speaking, if a country is able to launch a satellite, it can also develop an ICBM.

In addition to long-range missiles, North Korea has continued to develop mid-range missiles since the beginning of the 21st century. The Musudan, an intermediate-range ballistic missile (IRBM) with a range of 3,000km or more, has in fact already been deployed by the North. In 2006, the North also test-launched the Taepodong-2, which is believed to have a range of at least 6,700km. The Taepodong-2 can deliver a payload of high explosives or a chemical warhead, and it is estimated that the payload weight is between 650kg to 1,000kg, similar in scale to a nuclear warhead.

The only technology that North Korea has not demonstrated to date is the ability to bring a missile back into the atmosphere. With this technology in its grasp, North Korea will enter the ranks of countries that possess ICBMs capable of being equipped with a nuclear warhead.

“Since the North needs reentry technology to develop ICBMs, it has to launch a number of long-range missiles, and it will take around five years,” Hecker said. Indeed, Iran, which has close ties to North Korea, launched a satellite in 2009. Four years later in Jan. 2013, it announced that it had successfully brought a space ship back to earth. This implies that Iran successfully developed reentry technology.

“Of the various kinds of technology needed for a nuclear missile, North Korea has yet to obtain the technology for atmosphere reentry,” said Cho Kwang-rae, head of the Naro Launch Project at the Korea Aerospace Research Institute. “The key for reentry is developing synthetic materials that can withstand extremely high temperatures, but we have not been able to confirm whether North Korea has that kind of technological capability.”

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