North Korea's hovercraft-type battleships have been spotted by satellite for the very first time.The Seoul-based news channel YTN reported on Wednesday that a 34-meter-long vessel equipped with 30- and 57-milimeter cannons was caught in a satellite photo off the North's Daedong River, near the southwestern Nampo City in South Pyeongan Province.An improved version of a hovercraft built to assist Pyeongyang's special forces in carrying out a possible invasion of South Korea, the ship is twice the length of the existing wartime hovercrafts in North Korea's possession.On top of some 130 wartime hovercrafts of about 17 and 20 meters in length… which the North Korean military has anchored off both the East and West coasts a whopping 37-meter-long air-cushion vehicle was also seen docked at Wonsan port in the East Sea.[Interview : Shin In-kyun, PresidentKorea Defence Network] "It could likely transport medium to large-sized armed forces and tanks. And carrying a 30-milimeter cannon at speeds of at least 45 nautical miles per hour it would be able to raid regardless of the geographical features."Hovercrafts or air-cushion vehicles, supported by a cushion of air, are able to move over land, ice and water, as well as mudflats and swamps.The North's latest advancement in its capability to invade by water calls for officials in Seoul to come up with appropriate countermeasures.Choi You-sun, Arirang News.