A MASSIVE container ship called the Sea Teal is steaming off the west coast of Africa en route to China. But instead of its usual mountain of containers, a deadly cargo adorns its decks: a 220-foot Russian-made attack submarine, expected to arrive in late October.
The submarine is the second of four Kilo-class vessels China is buying from Russia as part of an ambitious plan to expand its Navy into one of the world's most formidable maritime powers.
The new additions to China's submarine fleet are part of what experts and US Defense officials say is an accelerating trend in the global proliferation of one of humankind's stealthiest and most deadly killing machines.
From the palm-fringed islands of Thailand to Iran's coast on the oil-rich Persian Gulf, submarines are emerging as one of the most important strategic weapons of the late 20th century - threatening to alter already tenuous regional power balances.
To the north, China has purchased a Russian-made Kilo-class submarine and is ratcheting up an indigenous construction program. And in the Middle East, Iran may add up to three more Kilo-class submarines to two it began operating in 1993, while Egypt is seeking to buy at least two new submarines to be built in the United States.
''We have numerous regional arms races emerging on an entirely new level here that are not only regional concerns, but global concerns,'' says Kay van der Horst, a specialist on submarines whose Washington-based International Center for Technology Assessment has begun a campaign for international controls on their sales. ''The submarine is one of the main tools for power projection in the future,'' says Mr. van der Horst.
Norman Polmar, a submarine expert at the Naval Institute, in Annapolis, Md., agrees. ''A lot of people are buying them. They are relatively cheap, and people look at them to offset what other people are doing.''
A case in point are Southeast Asian countries alarmed at China's naval expansion. Thailand earlier this year sought bids on four diesel-powered attack submarines. Singapore announced plans to buy its first submarine last week. Singapore and Thailand would then join a list of at least 44 states that possess one or more submarines.
These purchases are expected to herald a wave of submarine acquisitions in the region, with some experts predicting that as many as five Southeast Asian navies will be operating a total of 20 attack submarines by 2010. Currently, there are only two submarines in the region and both belong to Indonesia.
Experts attribute the new interest in submarines to a combination of economics, military strategy, and technological advances. Fueling the trend as well is fierce competition among weapons-producing powers, including the US, Russia, Germany, France, Britain, and China for slices of the shrinking post-cold-war arms market.
''Partly, more countries can afford submarines and partly they have recognized that in the face of certain military situations, they can be a relatively cheap way of leveling the playing field,'' says Ron O'Rourke, an analyst with the Congressional Research Service and a recognized authority on submarines.
''A principal mechanism for trying to exercise 'sea denial' are submarines,'' Mr. O'Rourke says. ''They make sense for a country that is operating in its home waters and which in a time of war cannot be assured of controlling the surface of the sea or the air above it.''
According to the US Office of Naval Intelligence, there are now more than 600 submarines worldwide. Nuclear-powered attack and ballistic-missile vessels are operated by the US, Russia, China, Britain, and France. The latter four also have diesel-powered attack submarines. Russia has the most submarines overall, followed by the US. Both are building new vessels, while slashing the overall size of their fleets.
The rest of the world's submarines are diesel-powered attack vessels, although India and Brazil are reportedly trying to build nuclear- driven boats. While surfaced, nonnuclear submarines run on diesel engines that charge batteries that drive them when submerged.
Though there are hundreds of these vessels, the numbers are somewhat deceptive. Many are obsolete, badly maintained, or poorly operated. Some no longer work.
North Korea, for instance, has the world's fourth largest submarine fleet, but its 36 vessels are paid little heed. They are old, easy-to-detect, Chinese-built Whiskey- or Romeo-class boats or its own Sang-O-class submarines. However, a senior US defense official says there are indications that the North Koreans have recently acquired Russian noise-reducing technologies.
A 1994 US Office of Naval Intelligence report lists Libya, along with Syria, China, Iran, North Korea, and Yugoslavia as ''high interest'' submarine-operating countries because of their proximities to key maritime ''choke points.'' But experts say Libya's four Soviet-made Foxtrot vessels have become dock-bound rust buckets for want of funds.
Of greater concern is the growing number of countries that are acquiring newer diesel-powered boats such as the Kilo. Some of these are giving serious pause to major navies.
One of those atop the US Navy's list is Iran. It is expected to add up to three more Russian-made Kilo-class submarines to two it began operating in 1993 near the Strait of Hormuz, the narrow waterway through which much of the world's oil passes. Many experts consider the Kilo-class sub to be the best diesel-power vessel around.
''The Iranians have surprised us by learning how to operate their submarines better and more quickly than we anticipated,'' says O'Rourke. ''They have conducted firings of weapons and fairly sophisticated exercises. That means we will have to be concerned about them.''
Another serious concern to the US Navy is China, which has the world's third-largest submarine fleet. Beside purchasing four Russian submarines, China is producing one to two submarines a year as part of a massive naval expansion effort.
Analysts who monitor submarine proliferation are more troubled, however, by the development of a new generation of diesel-powered vessels. They are faster, quieter, and better armed than their predecessors. Though they are slower and more limited in range than nuclear-powered boats, they are as good or superior in other respects as their atomic-driven cousins.
''Some of these nonnuclear submarines are available for procurement on the open market. This is a challenge to our antisubmarine forces,'' Nora Slatkin, a former assistant US Navy secretary and now a senior CIA official, told a congressional hearing in March. ''In addition to quality platforms, weapons systems, sensors, and processing power are available to countries intent on shifting the balance of regional power.''
Among other things, the new submarines incorporate advanced hull designs and other technologies that vastly reduce the sound and heat sources onto which sonar and other detection systems lock. That makes them extremely hard to find, especially in coastal waters, where they can ''hide'' amid the ''noise'' of heavy surface traffic and false signals reflected by debris and irregular sea beds.
Locating diesel-powered submarines is already a formidable task. During the 1982 Falkland Islands war, Argentina's only operational submarine at the time evaded 15 British ships and the antisubmarine aircraft of two carriers. It also came within torpedo range of the British fleet. Luckily for the British, all three of its shots missed.
The new submarines are far less vulnerable than their predecessors for yet another reason: they no longer need to surface frequently to run their diesels to recharge their batteries. This is achieved by a combination of advanced batteries and new air independent propulsion (AIP) systems that employ oxygen regenerating technologies or closed-cycle power plants.
Experts say new AIP submarines can remain submerged for weeks, an ability that previously only nuclear-powered boats possessed. One AIP vessel, the Type 212 made by Germany's Howaldtswerke-Deutsche Werft (HDW), is believed capable of traveling up to 4,000 miles at slow speed without having to surface. At similar speeds, conventional submarines must surface every four to 10 days.
AIP technology is also being produced in the US, France, Canada, Italy, South Korea, Russia, Sweden, and Australia.
Such developments could have a profound impact on areas such as South Asia, where Pakistan recently became the world's first developing state to buy AIP submarines, contracting for three French-made Agosta-class vessels. Once built, they will boost Pakistan's fleet to nine, fueling its rivalry with India. It is also reportedly looking at one of four Upholder-class vessels that Britain is offering for sale. Portugal may take the others, which would double its submarine fleet to six.
The increasing availability of advanced weapons and combat-control systems is adding to the lethality and attraction of the new nonnuclear submarines. Major suppliers are offering advanced torpedoes, antiship missiles that can strike an unsuspecting foe 90 miles away, and sophisticated mines.
''What is dangerous with these new weapons is that, due to their speed and due to the quieting of the new boats, the detection range seriously shrinks,'' says van der Horst. ''Basically, it's first come, first shoot.''
Advances in submarine-launched weapons are significantly altering the mission of subs. Once restricted to maritime operations and intelligence gathering, subs can sneak up to an enemy coast, fire at inland targets, and steal away without ever surfacing.
Proliferation is being fueled, experts say, by the number of countries building state-of-the-art submarines and submarine technology for export. They include Germany, Russia, Australia, Britain, China and Sweden.
''It's not difficult at all to go out an buy ... a German combat system and sonar system, combine it with a French air independent propulsion system and Dutch hull design, add in Russian sound-quieting techniques, and Swedish or US or other torpedoes,'' says the senior US Defense official. ''You end up with what I refer to as the consortium submarine. This is what we have to be concerned about in the future.''
The biggest exporter is Germany, which has sold more than 65 HDW-made submarines since 1970. Van der Horst says that Germany's customers included Pakistan, Chile, and Denmark.
The German government, to avoid enraging China, recently ruled out the sale of 10 HDW Type 209s to Taiwan. Taiwan is now reportedly discussing a purchase of Dutch-made submarines.
Russia, desperate for hard currency, is the world's second-largest exporter, having sold more than 45 submarines since 1970 to countries such as China, India, Algeria, Egypt and Iran. The Russian Navy has said it plans to build one diesel-powered vessel a year for export.
The relatively low costs of modern nonnuclear submarines make them attractive investments for many navies, experts say.
Prices average about $200 million per boat, without the supporting infrastructure. The new nonnuclear submarines also require only a small crew. Some experts say that with its advanced computer controls, the new boats in theory could be operated by a single sailor, although they carry standard crews of 29 to 30.
But submarine proliferation will grow for another reason, says Lora Lumpe of the Arms Monitoring Project.
Exporters Ms. Lumpe explains, have been sweetening sales by transferring to their customers the technology and know-how to build submarines themselves. Through such deals, India, Brazil, Argentina, and South Korea can now build diesel-powered attack submarines. The result is an explosion in potential exporters.
Once a country makes the massive investment to build submarines, ''the pressure to...use that production line will come into play,'' Lumpe explains.
Some experts are particularly concerned that such a scenario could occur in the US.
Last year, Ingalls Shipbuilding of Pascagoula, Miss., won administration approval to produce Type 209s under license from HDW. Their customer? Egypt, which wants two Type 209s. Using US military-assistance credits, which can only be spent on hardware made in the US, Egypt plans to purchase them from Ingalls.
Lumpe warns that once Ingalls establishes its Type 209 production base, economic pressures will compel it to deal with other recipients of military-assistance credits, such as Saudi Arabia.
''If the US Navy is concerned about the third world submarine threat,'' Lumpe explains, ''the last thing we should be doing is getting into the submarine-export business.''
Other critics say that by allowing Ingalls to export submarines, it will be more difficult for the US to oppose submarine sales by other countries to potential US adversaries.
Most experts agree that the US remains the preeminent submarine power, although some contend that its position is rapidly being eroded by Russian advances. Some experts also argue the US Navy has overstated the threat to justify huge budgets for new submarine construction.
Still, most experts agree that the acquisition of advanced nonnuclear submarines by potential US adversaries is cause for concern.
During the cold war, the US Navy focused on global containment of its now-defunct Soviet rival. Now, US global strategy anticipates a future dominated by regional contingencies, such as Somalia, in which US naval forces will be the first to reach the scene.
Critical time could be lost, if US vessels have to hunt modern enemy submarines, experts say.
''We can counter these submarines. But, they will slow us down,'' says O'Rourke. ''Naval forces must apply force at the early, critical stages of a conflict. Every moment, every hour, every day you are delayed is another moment, another hour, another day that enemy tanks can roll toward their objective.''
Says O'Rourke: ''There is an increasing recognition that the new submarines ... can create problems for even a major naval power like the United States.''