By Michael Peck, The National Interest
And how is South Korea is preparing to defeat them? With swarms of rockets fired from multiple rocket launchers mounted on small patrol vessels.
North Korea currently has about 300 fast attack craft, ranging from twenty-ton torpedo boats to a half-dozen Nongo-class surface effect ships—a sort of hovercraft—that weigh in at 200 tons, and carry a 76mm cannon and a North Korean version of Russia's Kh-35 antiship missile . The backbone of the North Korean force  is composed of more than 200 torpedo boats, armed with a couple of torpedo tubes and some machine guns or small cannon.
This mosquito fleet could hardly inflict more than a mosquito bite in an open sea battle against the South Korean and U.S. navies. But used in coastal waters, they could potentially prove devastating by conducting quick, surprise attacks with flotillas of boats to overwhelm the defenses of enemy ships. That such attacks would be suicidal wouldn't trouble Pyongyang if the prize was sinking or damaging a South Korean destroyer, a U.S. cruiser or even an American carrier.
South Korea's response was recently unveiled at the recent MADEX 2017 trade show, where Korean companies LIG Nex1 and Hanwha unveiled a rocket launcher system, specifically designed to stop North Korean swarm attacks. It will equip the South Korean navy's Patrol Killer Experimental, or PKX-B, patrol boats.
The launcher contains twelve canisters, each containing one 130mm rocket armed with an eighteen-pound warhead, according to naval Web site navyrecognition.com . The rocket has a maximum range of twelve miles, and mid-course guidance system that can adjust its trajectory in flight using GPS, inertial navigation, and data uplink, before an infrared homing system steers it onto the target. Significantly, the rocket launcher's fire control system can reportedly engage more than three targets simultaneously, which would put a dent in any wolfpack attack.
The rocket does have a minimum range of about two miles, which would create a dead zone that North Korean vessels could penetrate. But the forty-nine-foot-long, 200-ton PKX-B is also armed with a 76mm cannon. The first PKX-B is scheduled to be commissioned by the end of this year. The next three ships will be delivered by the end of 2018, and the four after that in 2020.
Other navies are looking at other solutions. In particular, the U.S. Navy is worried about swarm attacks, given that Iran will also use flotillas of small, fast boats to take on American warships in the narrow waters of the Persian Gulf. The navy recently test-fired a modified U.S. Army Hellfire antitank missile, reconfigured as an antiship missile, from a Littoral Combat Ship . The navy has also tested 57mm shipboard cannon and even robotic swarm craft to intercept enemy fast attack craft.
This first appeared in November of last year.