Fears, questions about North Korea’s growing nuclear arsenal
SEOUL, South Korea — North Korea’s latest missile launches are a demonstration of the country’s avowed ability to use nuclear force against South Korea and the mainland U.S. How immediate is that threat?
North Korea claims its nuclear forces are capable of destroying its rivals, and often follows its provocative weapons tests with launch details. But many foreign experts call the North’s claims propaganda and suggest that the country is not yet capable of hitting the United States or its allies with a nuclear weapon.
There’s no question that North Korea has nuclear bombs, and that it has missiles that place the U. S. mainland, South Korea and Japan within striking distance. What’s not yet clear is whether the country has mastered the tricky engineering required to join the bombs and the missiles.
ICBMs
North Korea has demonstrated that it has missiles that could fly far enough to reach deep into the continental U.S., but it’s not clear whether they can survive reentering the Earth’s atmosphere on arrival.
North Korea said it launched a Hwasong-15 intercontinental ballistic missile on Saturday to verify the weapon’s reliability and the combat readiness of the country’s nuclear forces. It’s one of three kinds of ICBMs the country has developed, along with the Hwasong-14 and Hwasong-17. All three are liquid-fueled, and North Korea has portrayed them all as nuclear-capable.
Launched almost straight up to avoid the territories of neighbors, the weapon reached a maximum altitude of about 3,585 miles and flew 615 miles, according to North Korean state media. The reported flight details suggest the missile could travel 8,080 miles or beyond if launched on a normal trajectory.
“These days, North Korea has been disclosing information about its launches in a very detailed manner to try to let others believe what they’ve done is genuine,” analyst Shin Jong-woo at South Korea’s Defense and Security Forum said. “But I think that’s part of their propaganda.”
There are questions on whether North Korea has acquired the technology to shield warheads from the high- temperature, highstress environment of atmospheric re-entry.
A South Korean biennial defense document released last week said it’s not clear whether the missiles can survive re-entry, because all of North Korea’s ICBM tests have so far been made on high angles.
Lee Choon Geun, an honorary research fellow at South Korea’s Science and Technology Policy Institute, said a normal trajectory would cause greater stress, as a warhead would spend a longer time passing through altitudes with high air density.
North Korean state media said the launch was made “suddenly” after a surprise order from leader Kim Jong Un.
“The Kim regime’s claims of short-notice launches are thus intended to demonstrate not only the development of strategic and tactical nuclear forces but also the operational capability to use them,” Leif-Eric Easley, a professor at Ewha University in Seoul, said.
Among them were huge canister-sealed missiles that experts say were likely a version of a solid-fuel ICBM that North Korea has been trying to develop in recent years. Solid-fueled systems allow missiles to be mobile on the ground and make them faster to launch.
Warheads
North Korea likely has dozens of nuclear warheads. The question is whether they are small enough to fit on a missile.
North Korea has so far performed six underground nuclear test explosions to manufacture warheads that it can place on missiles. Outside estimates of the number of North Korean nuclear warheads vary widely, ranging from 20-60 to up to about 115.
In a 2021 interview with 38 North, a North Korea-focused website, renowned nuclear physicist Siegfried Hecker, who has visited North Korea’s main Yongbyon nuclear complex numerous times, said that “20 to 60 is possible, with the most likely number being 45.”
Some experts argue that North Korea has likely already built miniaturized nuclear warheads to be mounted on missiles, citing the number of years the country has spent on its nuclear and missile programs. But others say North Korea is still years away from producing such warheads.
“After its sixth nuclear test, people accepted that North Korea really will have nuclear weapons. But they are still debating whether it has warhead miniaturization technology,” Mr. Shin, the analyst, said.
The North described its sixth nuclear test in 2017 as a detonation of a thermonuclear bomb built for ICBMs. It created a tremor that measured magnitude 6.3, and some studies put its estimated explosive yield at about 50 to 140 kilotons of TNT. In comparison, the pair of atomic bombs dropped on Hiroshima and Nagasaki during World War II — which killed a total of more than 210,000 people — yielded explosions equivalent to about 15 and 20 kilotons of TNT, respectively.
The biennial South Korean defense document said North Korea is estimated to have 154 pounds of weapons-grade plutonium. Some observers say that’s enough for about 9-18 bombs. The document estimated that North Korea has “a considerable amount of” highly enriched uranium as well.
Plutonium plants are generally large and generate a lot of heat, making them easier to detect. But a uranium enrichment plant is more compact and can be easily hidden from satellite cameras. North Korea is believed to be running at least one additional covert uranium enrichment facility, in addition to one at its Yongbyon complex.