The U.S. Navy is having a hard time shifting from a high seas fleet to a "littoral (coastal)" force. Since the end of the Cold War, and the disintegration of the mighty Soviet high seas fleet, all the action has been coastal. And along the coast, there are a lot more dangers. Not just the rocks and shoals (which can drive high seas sailors nuts), but also the larger number of weapons hostile forces can employ. Of the five U.S. Navy ships damaged by hostile fire in the last three decades, three were damaged by mines (in the Persian Gulf, one in 1988, by an Iranian mine, two in 1991, by Iraqi mines), one by an anti-Ship missile (Persian Gulf, 1986) and one by a suicide boat bomb (Yemen, 2000).
The navy's solution to this is a new class of ships designed for coastal operations. Called the Littoral Combat Ship (LCS), they are in reality small destroyers (or frigates, as the navy likes to call small destroyers, but the LCS will be much faster than the usual frigate.) A design competition is currently under way, and the navy is looking for a ship in the 2,000-3,000 ton class, highly automated (so that the crew can be under a hundred sailors) and laid out so that different modules (containers) of equipment and weapons can be swapped in and out. Thus an LCS could get a container of mine clearing gear and be a minesweeper. Or it could be equipped with sensors and weapons to find and attack submarines, or with guns and rockets to provide fire support for troops on land. LCS would also be suitable for landing SEALs or other commando type troops. Or with extra communications gear so it could act as a headquarters ship, or the LCS could simply carry supplies for troops ashore. That's the theory. There are already some LCS type ships out there, all under 1,000 tons displacement. The French have their 600 ton Lafayette stealth frigates, a design that has been licensed to other countries. Norway has its 260 ton Skjold fast attack ships and Sweden has it's 600 ton Visby class stealth corvettes.
The U.S. Navy doesn't want it's LCS to be as small as these other ships, because the LCS will have to travel long distances across oceans to get to where it is needed. All the other LCS type craft are meant for coastal defense. And it's the increasing number of coastal defenses that are giving the LCS designers headaches. In addition to mines and anti-ship missiles, there are also suicide boats, and the threat of suicide aircraft (of all sizes, even small, one engine propeller craft.) Another looming threat are faster, smarter and cheaper homing torpedoes that can be placed underwater and launched on command. LCS also has to worry about artillery and rockets and, if they get close enough to the coast, machine-gun and RPG fire. Not only does LCS have to be able to defend against all these threats, it has to be able to detect an attack before it hits. And all this with a small crew. Everything will depend on technology.
The navy expects to spend the next decade experimenting with the first few LCS ships that are built. It's a new form of warfare, although the Soviet Union and it's communist allies had long built hundreds of small coastal attack boats carrying torpedoes, missiles, mines and guns. Except for a few skirmishes off North Vietnam in the 1960s, the U.S. Navy has never had to confront this kind of coastal threat head on. But now they American fleet is regularly operating close to hostile, coastal waters. New ideas, new equipment and new ships are needed.