In mid-May the South Korean government presented clear evidence, in the form of torpedo remains with North Korean markings, that the north had sunk the southern corvette Cheonan. The torpedo was apparently a North Korean-made acoustic weapon, an example of which the South Koreans had previously recovered. It had seemed unlikely, at least to this author, that the North Koreans would deliberately have sunk a South Korean warship in South Korean waters. Against that, it seems that those using torpedoes often imagine that they are anonymous weapons.
For example, during the Spanish Civil War, German and Italian submarines anonymously sank merchant ships serving the Spanish Republic. Although it was obvious that the two fascist powers were responsible, no physical evidence was produced at the time (archival evidence has since made it clear that the Germans and Italians were to blame). The reason for anonymous attacks was obvious: the merchant ships were carrying important cargoes (often the arms that made the republic's fight possible), and there was hope that a submarine blockade would choke them off. There was probably also hope that the republic's friends would be intimidated. Since Germany and Italy were already involved on the ground, using "volunteers," their governments presumably did not consider the submarine attacks particularly risky. Above all, Spain was not a delicate place where confrontation could create a nuclear war (nuclear weapons did not yet exist, and wider European involvement was quite unlikely).
Korea, however, is technically a war zone in which powerful forces face each other across a narrow demilitarized zone, and both sides have nuclear weapons (and where the North Koreans have enough artillery and rockets to level Seoul soon after any war begins). Why would the North Koreans have chosen to attack a South Korean warship
It now appears that two or three North Korean midget submarines left their base with a mother ship shortly before the attack on the corvette and returned soon afterward. Was there something special about the South Korean ship Were the North Koreans interested in attacking some South Korean ship at the time, the particular ship sunk being unlucky enough to be thereTwo other facts may be relevant. One is that North Korean dictator Kim Jong-il, who hopes to make his son his successor (an oddity in a communist country) has reportedly had a stroke; he has been ill for years. Another is that last November South Korean naval forces intercepted a North Korean ship heading across the maritime border and damaged it, forcing it to return north. The attack on the Cheonan might be considered revenge for that action, or it could have been an attempt by the North Korean navy (or the military in general) to demonstrate its prowess.
Revenge might be likely, but it has little value unless the victim knows who has exacted it and a more or less anonymous torpedo would hardly seem to qualify (recall that at first the South Korean government badly wanted to imagine that the ship had been lost accidentally). On the other hand, it might be argued that by sinking the South Korean ship, the North Korean navy was demonstrating something important to their countrymen, who would (or at least could) know what had happened. In that case the question would be why it took the North Koreans almost six months to make their stroke if it did not involve any kind of new equipment on their part.
Yet another possibility is that both the encounters in November and March were incidental to a special operation being run by the North Koreans. Perhaps the ship the South Koreans intercepted in November was intended to land something or someone in South Korea (that has happened before). Maybe it took six months to create a replacement
i.e., an assassination team. In that case it might be that the midget submarine that torpedoed the South Korean corvette was covering an operation involving the other submarine or submarines, which were trying to land someone (or something) in the South. If they did not flee when the interception occurred, then possibly this story is continuing, and something is loose in South Korea. Alternatively, the appearance of the corvette may have aborted the operation, in which case its loss was not in vain.There remains the interesting point raised initially by the South Korean media: the North Koreans generally adopt a defensive stance when they plan an aggressive move against the South, and that would certainly include something like landing saboteurs or assassins. This time no such stance was detected. That suggests either that the North Koreans are becoming more sophisticated, or that there was a disconnect between the central government and those carrying out the operation. It may also be that the sinking was as much a surprise in Pyongyang as it was in Seoul because the decision was made at a low level. In that case, the most important aspect of the affair may be that it shows a leadership struggle is beginning (or maturing) in Pyongyang. Many observers suspect as much, although there has been little evidence (but many rumors, including attempted assassinations of Kim Jong-il).
Tracking Drug Subs
Meanwhile, the U.S. Coast Guard has announced that fully a third of the cocaine brought into the United States arrives on board semi-submersible boats built in South American jungles. Often they are described as drug-running submarines, suggesting a level of sophistication that is not really involved. Because they run nearly awash, they are effectively invisible to radar. Such boats are relatively simple and cost about $2 million to build, a fraction of the profit from just a single run. They are typically 30 to 60 feet long, with a crew of four (working in two shifts). Range suffices for a run from South America to the United States. When they are caught, the boats are scuttled to destroy the evidence.
A Coast Guard officer pointed to the difficulty of detecting such small targets in the vast area between the sources of cocaine in South America and the market in the United States. However, much of Cold War antisubmarine warfare was designed specifically to detect submarines in the vastness of the sea by exploiting long-range acoustic detection. Many of the same techniques (and, in some cases, the same technology) may be relevant to this problem. It could be time for the Coast Guard to recreate its earlier excellence in antisubmarine warfare.
A semi-submersible running its diesel may be almost invisible to radar and to airborne sensors, but it must project a great deal of noise into the water, and it should therefore be quite detectable by classic passive underwater sensors, such as the now largely decommissioned U.S. Sound Surveillance system (SOSUS). It must sound like a continuously snorkeling submarine without any kind of silencing, exactly the sort of target for which SOSUS was originally designed (later it could handle much quieter targets). SOSUS used large fixed arrays to detect and track underwater targets at great distances. From the 1970s on, the U.S. Navy also used T-AGOS ships towing SOSUS-like arrays. The long-range arrays typically offered only limited precision, but they could be used to cue shorter-range systems with greater precision.
For example, a cutter using a towed array should be able to detect a semi-submersible at a considerable distance. Cold War towed arrays were effective against much quieter targets at two or three convergence zones, up to about 105 nautical miles. Without any silencing, the craft would be far easier to detect than Cold War submarines. The craft should also be trackable by aircraft employing passive sonobuoys. In addition, it should be extremely vulnerable, because it has very little reserve buoyancy and hence will not survive any damage to its above-water hull. The usual Coast Guard helicopter armed with 50-caliber machine guns should be quite effective (the non-ricochet rounds the U.S. Navy currently uses against shallow-water mines might be particularly useful as a lethal threat). For that matter, anyone operating a semi-submersible would probably assume he had been detected when he heard the explosion of the small charge the U.S. Navy currently uses in shallow-water explosive echo-ranging sonobuoy systems. He might well choose to scuttle.
The main detection problem is that the waters between South America and the United States are filled with surface craft that have similar signatures. In the past, it would have been nearly impossible to sort wheat from chaff under such circumstances; what saved the day during the Cold War was that the Soviets used distinctive diesels and other noise-making elements. The drug-running semi-submersibles undoubtedly use standard automotive and small-boat engines, which are difficult to distinguish acoustically from others in legitimate service.
Now, however, it is possible to envisage computer systems easily capable of keeping track of thousands of boats and ships. Coast Guard radar aircraft can produce their own track files of whatever is operating on the surface in the areas involved. The two sets of files can be compared. What shows up acoustically but not on radar becomes suspect, and it can be investigated further. If the usual response to a Coast Guard helicopter overhead is to scuttle the craft, then much of the seaborne cocaine traffic could be stopped.