North Korea has started to equip its border patrol boats with U.S.-made Gatling machine guns, military sources said Tuesday.

"North Korea has been seen replacing its aging weapon systems with the rotary gun system," a military insider said. "If all the 380-something North Korean littoral combat boats are armed with the machine gun, this would pose an added threat to our Navy."

The sources said the weapon replacement seems to be aimed at strengthening North Korea's naval combat capabilities especially in close quarters. At present many smaller North Korean boats use hand-operated 30 millimeter cannons.

Local sources speculate that the North Korean guns are the 12.7 mm weapons made by General Electric. The machine gun has a cyclic rate of fire of 2,000 rounds per minute and can reach targets five to six kilometers away, although the effective range is 2 km.

The South Korean and U.S. militaries are currently tracking down how the machine guns ended up in the hands of North Korea, according to the sources.

Another military official also said the North is moving to apply stealth technology to its littoral combat boats in response to the South Korean Navy's move to employ high-speed, stealthy patrol vessels. (Yonhap)