North Korea has recently repositioned its 170 millimeter-caliber self-propelled howitzers in a frontline unit on the reverse slope, enhancing their survivability and further escalating artillery threats to South Korea, a government source said Sunday.

Hidden in mountain caves or tunnels, the howitzers used to come out through their gates facing the South in an emergency. But they will now move out through their newly-built northern gates, making it difficult for South Korea to strike them promptly and accurately.

“We have identified recent changes in the shape of the caves for the howitzers in an artillery unit under the North’s 4th Corps in Hwanghae Province. They have closed the southern entrances of the artillery caves and made the northern entrances,” the source told media.

“It was relatively easier for our forces to destroy the southern entrances with our artillery and missiles. But now, it is more difficult for us to neutralize the artillery threats as the howitzers face the north in the opposite direction.”

Pyongyang’s repositioning of its artillery came as the South has bolstered its counterstrike capabilities with the deployment of new weapons systems such as Israeli-made Spike missiles, which are capable of launching precision strikes on the North’s hidden coastal artillery.

In an armed conflict, the North’s howitzers will move out through the northern gates, fire at its enemy forces and return to their caves.

To destroy the artillery caves, Seoul plans to use combat aircraft to release the Guided Bomb Unit-28, better known as bunker busters, or the GPS-guided Joint Direct Attack Munition. But with the artillery put on the reverse slope, it would become more difficult to conduct aerial strike missions, experts say.

The North’s 170-mm howitzers have a range of 54 kilometers, putting the Seoul metropolitan area within striking range. The North is said to have reinforced its mountain caves and underground facilities to better protect its artillery forces.

Meanwhile, the U.S. has been making a detailed map of North Korea’s underground military facilities in preparation of a military contingency, and running an educational program for both U.S. and South Korean officers, according to Yonhap News.

Army Maj. Park Sung-man of the Special Warfare Command revealed in his contribution to a monthly magazine of the Joint Chiefs of Staff that the U.S. Forces Korea has been running the program called “UGF,” or Underground Facility.

The U.S. Army has run the UGF program since the mid-1990s and instituted the program for the USFK in 2007. South Korean officials have participated in the program since last year.

The USFK spent more than six years making a map of North Korea’s underground facilities based on accounts from North Korean defectors.

Alarmed by the massive air strikes by the U.S. during the 1950-53 Korean War, the North has been paying much attention to the underground fortification. The North is believed to have some 6,000-8,000 underground military facilities.

By Song Sang-ho

(sshluck@heraldcorp.com)