The  Arleigh  Burke  class  represents  a  return  to all-steel construction and incorporates electromagnetic pulse hardening, enhanced firefighting features, and a collective  protection  system  to  provide  protection against nuclear, chemical, or biological contamination. This vital equipment is distributed through the ship, giving  the  ship  improved  blast  and  fragmentation protection, which lets them to survive a hit and continue to fight. Frigates.—The classification “frigate” designates ships used for open-ocean escort and patrol. Frigates resemble destroyers in appearance, but they are slower, have only a single screw, and carry less armament. Frigates are slowly being replaced by DDGs. The Oliver Hazard Perry class is the only class of guided-missile frigates  still  commissioned.  The  USS    Ingraham (FFG 61) (fig. 8-20) carries the following armament: A single 76-mm, .62-caliber Dual-purpose gun A 20-mm Vulcan/Phalanx rapid-fire gun A single launcher for Harpoon missiles Two SH-60 LAMPS III helicopters Two Mk 46 triple-torpedo tubes Submarines.—The Navy deploys two classes of submarines  attack  submarines  (SSNs)  and  ballistic missile submarines (SSBNs). The mission of nuclear attack  submarines  (SSNs)  is  to  locate  and  destroy enemy ships and submarines. They also act as scouts, deliver supplies and personnel to locations in enemy territory, and perform rescue missions. Fleet ballistic missile submarines (SSBNs) deliver ballistic missile attacks against assigned targets from either a submerged or surfaced condition. Most of the SSBNs are being converted to carry Trident missiles, which have greater range and multiple warheads. A new class of submarine, the Ohio class (fig. 8-21), has been developed for the Trident missile. The Ohio class is the largest undersea craft developed by the Navy. It displaces 16,600 to 18,700 tons. The size of the Trident submarine is dictated by the larger size missile required for ranges of 4,000 to 6,000 miles and by the larger  reactor  plant  required  to  drive  the  ship.  The submarine has 24 tubes for the Trident missile and 4 torpedo tubes located in the bow. A nuclear-powered attack submarine, like that of the Sturgeon class, displaces 3,800 to 4,700 tons, can do more than 20 knots, and has four torpedo tubes. The newer Seawolf class fast-attack submarine displaces about 9,137 tons, has four torpedo tubes, and can attain speeds  of  over  35  knots  (fig.  8-22).  The  Seawolf performs  a  variety  of  crucial  assignments,  from underneath the Arctic icepack to all regions anywhere in the  world.  Its  missions  include  surveillance, intelligence  collection,  special  warfare,  covert cruise-missile strike, mine warfare, and anti-submarine and anti-surface ship warfare. The Seawolf’s stealth characteristics make it the world’s quietest submarine. Early submarines were named after marine life. The first SSBNs, however, were given names of persons well known  in  American  history,  like  USS    George Washington, USS   Patrick Henry, and USS   Lafayette. The new fast-attack submarines (SSNs) are named after American cities, like the USS   Los Angeles, _USSAlbuquerque, and USS   Memphis. The Tridents (SSBNs) are being named after American states, like the USS  Ohio  and USS  Michigan. OT H E R    C O M BATA N T S . — O t h e r    s h i p s classified as combatants are amphibious warfare ships and mine warfare ships. Amphibious  warfare  ships.—An  amphibious assault operation is the fastest means of landing large numbers  of  personnel,  equipment,  and  supplies  on enemy-held territory. The lessons learned during World War II, Korea, and Vietnam have resulted in the U.S. Navy having the largest and most capable amphibious force in the world. With the introduction of new classes of ships and new types of landing craft and helicopters, the U.S. Navy can conduct an amphibious operation almost anywhere in the world. A m p h i b i o u s   a s s a u l t   s h i p s .  Ta r awa - c l a s s amphibious assault ships (LHAs) are able to embark, deploy, and land a marine battalion landing team by helicopter, landing craft, amphibious vehicle, or by a combination of these methods. The Tarawa-class ships have 9 Sea Stallions and 12 Sea Knight helicopters plus 6    Harrier    attack  planes.  It  also  carries  2  RAM 8-20 Student Notes: