North can hit all of South, U.S. bases in Japan: Experts

North Korea has noticeably advanced its tactical nuclear weapons program to target not only the rest of the Korean Peninsula but also U.S. bases in the region, according to experts in Seoul...

A photo released by the official North Korean Central News Agency on March 20 showing a rocket launch during a tactical drill to bolster the country's war deterrence and nuclear counterattack capability at an undisclosed location in North Korea on March 18 and 19. [EPA/YONHAP]

North Korea has noticeably advanced its tactical nuclear weapons program to target not only the rest of the Korean Peninsula but also U.S. bases in the region ,according to experts in Seoul.

“North Korea has developed a unique method of loading nuclear warheads onto missiles like loading bullets into a gun,” an analyst in Seoul said on condition of anonymity. “Because it cannot compete directly in nuclear power with existing nuclear superpowers such as the United States, China and Russia, the regime appears to have chosen the path of developing tactical nuclear weapons instead.”

North Korea currently appears to have at least eight types of missiles that can carry Hwasan-31 tactical nuclear warheads to target all of the Korean Peninsula or even U.S. bases in Japan.

These missiles, including the KN-23, a short-range ballistic missile considered the North Korean version of Russia's Iskander missile, and the Haeil, a nuclear-capable, unmanned underwater drone designed to attack by setting off large, radioactive tidal waves, were in a poster of missiles seen hanging behind North Korean leader Kim Jong-un as he examined a Hwasan-31 warhead in a photo released by North Korean state media on March 28.

Reports in South Korea estimate the Hwasan-31 to be 40 centimeters (15.7 inches) to 50 centimeters in diameter, 90 centimeters in length, 150 kilograms (330 pounds) to 200 kilograms in weight, and 4 to 7 kilotons in power.

While neither the U.S. nor South Korean government has confirmed whether North Korea has successfully miniaturized the Hwasan-31 tactical nuclear warhead so it can be mounted on a missile, many experts say the North has likely done so.

“It seems that the nuclear warhead was designed in the particular shape of a bullet to facilitate its mounting on the projectile,” said a government official on condition of anonymity.

Many short-range missiles developed by North Korea in recent years are capable of pull-up maneuvers and other countermeasures that make them harder to intercept.

The KN-23 is able to pull-up midway, while the KN-24 — also known as North Korea's version of the short-range ballistic missile ATACMS — is able to spray submunitions from the sky, allowing them to defeat South Korean or U.S. antimissile defense systems such as the Patriot Missile Segment Enhancement (PAC-3 MSE) interceptor or Terminal High Altitude Area Defense (Thaad) system, which intercept missiles in the final stage based on predicted trajectories.

Similar problems apply for the KN-25, which can be launched multiple times from a super-large multiple-launch rocket system.

The mix of conventional warheads and tactical nuclear warheads by the North could pose further challenges to the South’s defense strategies, some experts say.

"Given the short depth of the Korean Peninsula, we barely have time to intercept a missile,” said Lee Chun-geun, senior research fellow at Science and Technology Policy Institute. “It will be difficult to intercept a missile mounted with a tactical nuclear warhead."

Kwon Yong-soo, a senior research fellow at the Korea Institute for Military Affairs (KIMA) and a former professor at Korea National Defense University, said that North Korea didn’t simply re-invent the Iskander, but made sure that its “evasion maneuver performance has been improved significantly.”

Several experts in South Korea including Park Yong-han at the Korea Institute for Defense Analyses released a report in January estimating that North Korea aims to possess as many as 300 nuclear warheads long-term, which, if achieved, would put North Korea on par with China.

During his visit to the Nuclear Weapons Institute last month, North Korean leader Kim also ordered production of weapons-grade nuclear material to accelerate the production of powerful nuclear weapons.

The South Korean general public is well aware of the North’s recent rhetoric and actions related to nuclear weapons, with as many as 76.6 percent of South Koreans surveyed by the Chey Institute in January calling for the South to develop its own nuclear weapons to counter the nuclear threat from the North.

BY CHUNG YEONG-GYO, ESTHER CHUNG [chung.juhee@joongang.co.kr]