In September 2015 North Korea was seen moving at least six of their new high-speed patrol vessels south and basing them near the South Korea sea border. This was meant to be some kind of threat, but mainly it gave South Korean naval intelligence an opportunity to get a better look at these new designs. There about ten of these new patrol boats, whose development began after 2000 and first appeared at sea in the last few years. These boats vary in size (35-40 meters/112-130 feet long) none appear larger than 500 tons. These boats are characterized by stealthy design, high speed (up to 100 kilometers an hour or more) and light armament (autocannon, maybe a 76mm or 57mm gun or 30mm autocannon plus a few torpedoes or anti-ship missiles.)
These new ships have been referred to as VSV (Very Slender Vessels) or the Nongo class. Because these are among the few new warships North Korea has built since the 1980s South Korea keeps seeking more information. That is difficult to come by because these new ships are not seen at sea much. This indicates that their radical new design, which achieves high speed via the “surface effect” design. That approach is known to be difficult to implement and the North Korean version may not be working as intended. Now the South Koreans are hoping some VSVs will get a chance to demonstrate what exactly they can do.