Anyone who thinks the North Koreans will sit back passively and allow their ships at sea to be stopped and searched for nuclear weapons or missile components should reflect on a little-known sea battle that took place off the southern coast of Kyushu.

The December 22, 2001, running firefight pitted the Japanese Coast Guard and the North Korean "spy ship" (Japan's phrase) Changyu 3705. Eventually the Korean vessel scuttled itself, taking its 10-man crew to the bottom. Three Japanese Coast Guardsmen were wounded.

President Barack Obama and Japan's Prime Minister Taro Aso have both pledged to carry out the latest United Nations resolution allowing member nations to stop and search North Korean vessels suspected of carrying illicit weapons material or missile components. (On Monday it was reported that a US Navy destroyer was already trailing one North Korean cargo ship in international waters.)

The resolution came in the wake of the North's provocative multistage missile tests in April and its setting off of its second nuclear device in May. It calls on UN members to inspect all cargo to and from the North in their territorial waters if they have "information that provides reasonable grounds" that the cargo includes nuclear and missile related items.

The 2001 shootout began in the late afternoon when a coast guard cutter and several patrol aircraft were dispatched to investigate a suspicious vessel operating inside Japan's economic exclusion zone. Ignoring orders to halt, the suspicious vessel attempted to escape. The cutter fired warning shots across the bow, into the sea and eventually directly into the bow of the ship.

The Northern vessel fired back, spraying the coast guard cutter with bullets from automatic rifles and rocket-propelled grenades. It was later determined that the vessel was armed with a Russian-made 14.5 mm ZPU-2 anti-aircraft gun, concealed in a cabin behind the wheelhouse although it was not fired at the coast guard vessel.

At around 10 p.m. the Changyu scuttled itself and sank about 390 km west of the Japanese island of Amani Oshima. None of its 10-member crew survived, although the coast guard did recover several bodies floating in the water.

The Japanese government was curious enough about this ship and what it was up to that it took the trouble, and the considerable expense (about US$50 million), to raise it and associated debris from 90 meters of water to examine it more carefully.

The ship is now on public display in a barn-like building that makes up the Japan Coast Guard Museum on the Yokohama waterfront, a trophy vaguely reminiscent of another spy ship, the USS Pueblo, which was captured by North Korea in 1968 and put on display in Wonson harbor.

The 33-meter ship is rusted and brown from its burial at sea, the bullet holes from the coast guard's 20 mm machine gun are clearly visible at the bow. Aside from associated debris, there are no other displays in the room. The museum is open to anyone free of charge.

The Changyu was clearly designed to look like a fishing boat of undetermined nationality (it has fake name plates in Chinese characters), but a close look reveals anomalies. Where the hold forward of the wheelhouse would normally store the catch was a Russian-made high speed engine capable of pushing the ship to 33 knots, considerably more powerful than a common fishing boat.

At the stern, two doors open to permit a smaller ship to exit from the mother ship. The smaller boat was designed to look like a squid fishing boat but one with an unusually powerful power assembly. Near the stern doors were explosives designed to scuttle the ship if necessary.

On display are other intriguing items that were scattered on the sea bottom. Among them were assorted AK-47 automatic rifles, hand grenades, rocket launchers, the ZPU anti-aircraft machine gun and a curious underwater scooter shaped like a torpedo, plus uniforms and a button with the face of Kim Il-sung.

It is clear that the museum serves a political purpose. As its brochure states, it was opened "to allow citizens to understand the current situation of the waters around Japan and the importance of marine patrols." The "situation' could mean anything but most likely points to Japan's obsession with North Korea's abduction of some of its citizens in the 1970s and 1980s.

One can easily imagine the smaller ship sneaking into a Japanese harbor (maps of Kagoshima were recovered from the sunken vessel) or along the coast to land secret agents or pick up kidnap victims, such as then 13-year-old Megumi Yokota, who was abducted along the Sea of Japan coast in 1977 and taken to the North

In this instance, it seems more likely that the ship was engaged in routine drug smuggling. The incident was videotaped, and one segment shows somebody on board throwing some items over the side. Recovered from the floor was a water-logged Japanese mobile phone, but investigators were able to use phone company records to trace calls to gangsters on Kyushu. Several prosecutions resulted.

Since the sea battle, the coast guard has boosted the size and range of armaments aboard its newer patrol ships, allowing them to fire effectively at a more distant range, presumably out of range of handheld automatic weapons and RPGs.

Indeed, Tokyo has been expanding the coast guard, which currently boasts 89 armed vessels, and enlarging its mission in recent years. The Coast Guard Annual Report for 2009 includes for the first time a section devoted to protecting Japanese territorial waters from intrusions by neighboring states.

This includes the waters off the Senkaku islands in the East China Sea, claimed by China, Japan and Taiwan. The coast guard has taken the lead in policing these waters, and in December caused an international incident when a cutter collided with a Taiwanese sports fishing boat.

The Japanese government has submitted a bill to the Diet that would allow Japan's maritime services to inspect North Korean cargo on the high seas in accordance with the new UN mandate. Interestingly, Aso designated the coast guard as the agency to do the searches, not the Maritime Self-Defense force (navy).

Apparently the government felt that using the coast guard rather than the navy would prevent these close encounters on the high seas from turning violent, although the "spy ship" incident would suggest that the North Koreans don't necessarily differentiate much between the two sea services and they won't give up the ship without a fight.