SEOUL, South Korea — North Korea is touting technological progress in its nuclear program, saying after a nuclear test Friday that it can now produce "smaller, lighter and diversified nuclear warheads of higher strike power." But it is also making strides in its missile program, analysts say — advances that could enable it to outsmart missile defense systems, which could make the missiles more attractive to potential customers.
North Korea conducted what it called a "nuclear warhead explosion test" Friday. The country has conducted only five nuclear tests since its program began, but this is the third since Kim Jong Un took power at the end of 2011 and its second this year alone.
Under Kim's leadership, North Korea has also sharply accelerated the pace of missile testing, with almost two dozen launches this year alone. While many of this year's tests have not been successful and there are still many unknowns about North Korea's nuclear and missile programs, there have still been noticeable — and concerning - improvements.
"It seems like North Korea is trying to qualitatively improve its missiles and develop options to evade or fool U.S. missile defenses," said Kelsey Davenport, director for nonproliferation policy at the Arms Control Association. "If this continues unchecked, they could develop an inter-continental ballistic missile that could pose a threat to the United States in the next decade."
In its most recent salvo, North Korea launched three medium-range missiles Monday as China, which had joined the international condemnation of last month's submarine-launched ballistic missile, was hosting the G20 summit in Hangzhou.
The rockets flew about 600 miles — putting Hangzhou within range. But they were sent in the other direction, falling inside Japan's air defense identification zone.
Arms control experts have since been poring over photos of the launches released by the North Korean media. Video footage, complete with stirring revolutionary music, shows three missiles being launched in the space of a minute from trucks parked on a highway south of Pyongyang.
The location is within the security belt protecting Kim and the other regime elites in the capital, said Michael Madden, editor of the North Korean Leadership Watch website. That meant the drills could be simulating the collapse of the state or the presence of hostile forces within the country, he said.
But it was the modifications to the missile that surprised the rocket scientists at the James Martin Center for Nonproliferation Studies in Monterey, Calif. It appears that North Korea has extended the distance a short-range Scud can fly, essentially turning it into a medium-range missile, which the North Koreans call the Rodong.
That means that a longer-range missile could be wheeled out on an existing Scud transporter — obviating the need to produce new trucks. Syria is among the countries thought to have bought short-range Scuds from North Korea, in about 2000.
"This is a really nice upgrade," said Jeffrey Lewis, director of the East Asia Nonproliferation Program in Monterey. "Countries looking to buy North Korean missiles are probably looking at this and thinking, 'Ooooh, that's nice.' "
North Korea has been concentrating on developing road-mobile missiles that can be fueled in a shelter or tunnel, instead of on a traditional launchpad that can be detected by satellites - and theoretically invite a preemptive strike.
Japan's self-defense forces did not detect Monday's launch in advance, the Nikkei newspaper reported, also saying this underscored the limits of Japan's traditional defense capability program.
In the past, when activity had been seen around the launchpad, Japan's self-defense forces would roll out Patriot Advanced Capability (PAC-3) interceptors at the defense ministry headquarters in Tokyo. But road-mobile missiles can be readied for launch in a matter of minutes, cutting the time available to respond.
Japan is "very concerned" that North Korea has launched so many different missiles in such a short period, said Atsuya Tanimoto of the Japanese Defense Ministry's intelligence analysis office. "North Korea is improving its technology," he said.
North Korea also appears to be looking for other ways to avoid interception, no doubt motivated by South Korea's recent decision to host a Terminal High Altitude Area Defense (THAAD) antimissile unit for the U.S. military. The battery is due to be deployed to a site south of Seoul next year.
But by firing the three missiles within the space of a minute, rather than over the usual course of an hour or so, North Korea appeared to be testing a way to make it more difficult to intercept incoming missiles, said Joseph S. Bermudez Jr., a military analyst affiliated with the Washington-based U.S.-Korea Institute at SAIS.
"This launch was probably designed to test not only operational readiness but to develop tricks to defeat antimissile defenses in Japan and South Korea," Bermudez said.
"When you launch in a barrage at the same time, it complicates missile defense. So they've shown they have not just the technological capability but the operational capability for simultaneous launches."
Furthermore, it appeared that missile tested Monday separates after launch — making it harder for missile defense systems to intercept.
"When a solid warhead remains attached to the missile, it's easier to hit because it's a bigger target," Lewis said. "If you were in Egypt, staring at Israel, you might really like a warhead like this."
North Korea has not demonstrated any capacity to make a nuclear warhead small enough to attach to a missile, let alone the ability to deliver a nuclear-tipped missile to a target.
Still, the progress in its medium-range missile program follows observable advances in North Korea's quest to launch missiles from sea as well as from land.
North Korea was ridiculed for apparently photoshopping a ballistic missile launch from a submarine in May. But last month it successfully launched a missile from a submarine near its east coast port of Sinpo. It flew about 300 miles toward Japan before falling into the sea.
This showed that its missile program might be progressing faster than originally expected, said John Schilling, an aerospace engineer who studies North Korea's missiles.
"However, this does not mean it will be ready next week, next month, or even next year," he wrote in a commentary for the 38 North website.
But North Korea's submarine-launched ballistic missiles could be operational by the second half of 2018, he wrote.
Concurrent with making progress on its delivery systems, North Korea has also been refurbishing its old missile production infrastructure.
Kim visited the January 18 General Machinery Plant, which makes sensitive missile components, at the end of last year and joked that it looked so good, visitors might think they were in a resort.
International sanctions imposed through the United Nations, as well as direct sanctions from the United States, South Korea and Japan, have been designed to cut off North Korea's ability to buy parts for its nuclear and missile programs, as well as stanch financial flows.
But the steady rat-a-tat of missile tests suggests that North Korea has plenty of missile parts to play with.
Some American officials suggest that North Korea might be racing against the clock, trying to test and make as much progress as it can before the latest round of sanctions really bites.
While Bermudez warned against getting too excited about the most recent developments, saying they simply reinforce what had been seen previously, Lewis said the developments should disabuse anyone of the notion that North Korea was not serious about its missile program.
"They're testing at a really fast rate because the program is real," he said."The idea that this is a Potemkin missile program is just nonsense."