I was recently privileged to visit the Los Angeles-class fast attack sub USS San Juan (SSN 751) at the New London Naval Submarine Base in Groton, Connnecticut.  San Juan's executive officer was my escort for the dock tour.  The ship was commissioned in 1988, back while the Cold War was still being fought.  But the more the XO talked, and the more things he showed me, the more I saw proof that San Juan and her sisters are indispensible capital ships of the 21st century.  Each of the Los Angeles boats still in service has received repeated major upgrades and refits during her lifetime.  It's not exaggerating much to say that these magnificent vessels have little in common today with what they were like when first launched, except maybe for their pressure hulls and framing.

As a case in point, America's newest commissioned SSN, USS Texas, second in the transformational Virginia-class, happened to be tied up next to San Juan during the tour.  San Juan's XO said that his own ship's combat systems (sonar signal processors and displays, weapons control, etc.) were actually of a more advanced generation than what Texas was built with -- Texas would get the new system installed while she was in Groton.

Other significant enhancements to the L.A.-class include much better secret quieting technology and improvements to the propulsion plants.  Major leaps forward in sensors include retrofitting the TB-29A "thin line" towed array, more sensitive and versatile that the earlier "fat line" TB-16D.  Reportedly, the revolutionary sonar wide-aperture arrays of the Seawolf and Virginia classes have been or will be mounted onto the L.A. boats, starting with San Juan and including all her 22 newer sisters.  These wide-aperture arrays allow instant ranging of detected targets.  No more the seemingly endless "polishing the cannonball" of a target motion analysis to get a good firing solution on an adversary!
 
Just as important as the Los Angeles platforms are the fish and cruise missiles they carry.  This includes the latest mod of the Mark 48 Advanced Capability torpedo, which with open computer architecture and C-BASS littoral-capable sonars is the active-duty American submariner's weapon of choice.  The Tactical Tomahawk, which can loiter in flight and be re-directed toward fleeting high-value targets of opportunity, fleshes out the L.A.-class armaments suite.

Developmental off-board, remote controlled and retrievable mine reconnaissance probes are gradually becoming operational in L.A.-class torpedo rooms.  The dry-deck shelters that can be mounted topside aft of the sail, to support SEAL operations, are perhaps more relevant now in the War on Terror than ever before.  Nor is active defense neglected; the pods on dihedral fins at most ships' sterns, used to deploy towed arrays, are being modified to also hold ejectors for 5-inch countermeasures, supplementing the smaller ones that can be fired from internally.
 
The best proof of all that Los Angeles subs remain fully capable warships of tomorrow is that Los Angeles herself, SSN 688, just celebrated her 30th birthday.  Yet in 2007 she and her crew will head out on deployment once more, to the vital and volatile nautical arena of the Western Pacific.