By Oh Seok-min
SEOUL, March 26 (Yonhap) -- North Korea's new ballistic missile test-fired this week could further bolster the country's tactical nuclear arsenal and pose serious threats to South Korea and beyond by challenging its missile defense system, experts said Friday.
On Thursday, the North fired what appears to be two short-range ballistic missiles into the East Sea, the Joint Chiefs of Staff (JCS) said, in its first ballistic missile test since the launch of the U.S. Joe Biden administration.
The North's official Korean Central News Agency (KCNA) said early Friday that they were a "newly developed new-type tactical guided projectile" with a 2.5-ton warhead, which employs "the core technology of tactical guided projectile that was already developed."
Given those descriptions and outward appearance, experts said the missile appears to be an upgraded version of the North's KN-23, modeled after Russia's Iskander mobile ballistic missile.
The variant was first showcased during a military parade held in Pyongyang in January and had not been tested before.
"This gives North Korea the flexibility to use a not-so-compact nuclear warhead on this missile," Vipin Narang, a professor at the Massachusetts Institute of Technology, tweeted. The original KN-23 has a 1-ton payload.
Chang Young-keun, a missile expert at the Korea Aerospace University, noted that it seems hard to believe the North's claims and more tests will be needed to verify the system, but the new missile "is powerful enough only with conventional explosives and would serve as a tactical nuclear weapon."
In January, leader Kim said during a party congress that his country is developing new weapons systems, such as a nuclear-powered submarine, advanced warheads and hypersonic weapons. Vowing to further bolster its nuclear arsenal, he also called for making its nuclear weapons small, lighter and tactical.
"Kim Jong-un promised work on tactical nuclear systems. One way to do that is to design light compact nuclear warheads to mate with short range missiles. The other is to design your short range systems to carry a 2.5-ton warhead," Narang said.
The upgraded version can also be seen as Pyongyang's response to the South Korean powerful ground-based Hyunmoo-4 missile.
"The Hyunmoo-4 has a 2-ton payload and has a maximum range of 800 kilometers. North Korea now claims that it is developing a comparable item," professor Chang said.
According to KCNA, the missiles accurately hit a target set in the waters 600 kilometers off the east coast, while the JCS said they flew around 450 kilometers with an altitude of 60 km.
"Due to its pull-up maneuver, the figures could differ," said Shin Jong-woo, a senior analyst at the Korea Defense Security Forum in Seoul.
Rather than following the typical parabolic trajectory of a missile, the KN-23 shows a more complicated path by doing a so-called pull-up maneuver over the course of its flight.
The new Iskander is also believed to use a transporter erector launcher (TEL) with 10 wheels, compared with the previous version of a four-axle TEL, which indicated that it is longer so as to be capable of flying further.
The previous version is believed to be capable of flying around 400 to 600 km, which put all of South Korea within its range.
The mobile, solid-fuel weapon is also hard to detect, and the low peak apogee could neutralize the advanced U.S. anti-missile defense system (THAAD), experts said.
KCNA said that the North's Academy of Defence Science confirmed "the irregular orbit features of low-altitude gliding leap type flight mode already applied to other guided projectile," as well as "the reliability of the improved version of solid fuel engine" by conducting several engine ground jet tests and their test-firing processes.
The JCS said it is analyzing the projectile in close coordination with the United States.
North Korea has been working on developing short-range solid-fuel missiles in recent years while suspending nuclear and long-range tests.
Under the U.N. Security Council resolutions, North Korea is banned from all ballistic missile activity.
Nuclear envoys of S. Korea, U.S., Japan condemn N. Korea's stipulation of nuclear policy
Memorials commemorating Itaewon crowd crush to be erected at accident site
Royal palaces in Seoul available for free during Chuseok holiday
Pentagon's CWMD strategy document calls N. Korea 'persistent threat'
Opposition leader Lee again proposes talks with President Yoon
N. Korea stipulates nuclear force-building policy in constitution
5 years after signing, future of inter-Korean military accord unclear
Kim-Putin summit highlights strategic push to expand cooperation
In desperation, N. Korea, Russia turn to one another for mutual assistance rivaling U.S.-S. Korea cooperation
N. Korea probably sees technical advance in spy satellite launch despite botched 2nd attempt