New Threat Upgrade

The Program
New Threat Upgrade (NTU) was a United States Navy program to improve the capability of ships equipped with Terrier and Tartar anti-aircraft systems. USS Mahan (DDG-42) was selected to install and test the Terrier New Threat Upgrade (NTU) Combat System with the improved Standard Missile Two Block II (Extended Range). Testing lasted from October 1981- March 1985. This New Threat Upgrade system made USS MAHAN the most capable AAW ship afloat. New Threat Upgrade allowed the full use of newer Standard missiles (SM-2) and improved the interoperability of the radar and computer systems aboard the ships. The system allows the ships to which it was fitted to time share illumination radars for multiple missile interceptions in a manner similar to the Aegis Combat System. Some sources indicate that NTU ships were superior in some respects to Aegis ships of the same era, particularly in the area of user interface. They were inferior in that they could not deal with a saturation missile attack as well as Aegis vessels. The lower levels of funding available to the USN after the Cold War lead to most of the NTU ships being retired early, because of high cost of operation compared to newer vessels. As a result, the United States Navy no longer fields any NTU capable ships and most newly constructed ships have the Aegis weapon system.

Modifications to Existing Ships
The New Threat Upgrade to the Leahy class included massive remodeling of the ship from food service space rehabilitation to a main propulsion system overhaul. Entire systems were removed and replaced, for example the AN/SPS-40 air-search radar was replaced with the AN/SPS-49 air-search radar. The upgrade was also quite expensive and the ships modified didn't serve much longer after the modification. For example, USS Gridley (CG-21) received NTU in 1991 at a cost of $55 million but was decommissioned in early 1994.

End of the Cold War
The Cold War ended shortly after the expensive New Threat Upgrade occurred and all ships that received the upgrades were decommissioned within six years of their upgrade. The USS Texas (CGN-39) was decommissioned during the upgrade.

KDX-II Class
The Navy of the Republic of Korea uses a NTU derived system for its Chungmugong Yi Sunshin class destroyers.

NTU systems

 * AN/SPS-49(V)5 - A 2D Air Search Radar (Bearing and range)
 * AN/SPS-48E - A 3D Air Search Radar (Bearing, range and height)
 * AN/SYS-2(V)1 Integrated Automatic Detection and Tracking System (IADTS)
 * (A)CDS - (Advanced) Combat Direction System
 * WDS Mk 14 - Weapons Direction System
 * Mk 74 Tartar and Mk 76 Terrier Fire Control Systems (AN/SPG-55B radar for Terrier ships and AN/SPG-51 for Tartar)
 * AN/SYR-1 Communications Tracking Set, used for SM-2 missile downlink
 * Mk 10 twin-arm manual launcher, Mk 13 single-arm automated launcher and Mk 26 twin-arm, automated missile launchers
 * RESS - Radar Environmental Simulator System

NTU ships
These classes had some of their units modified with the New Threat Upgrade.
 * Belknap class cruiser
 * California class cruiser
 * Charles F. Adams class destroyer - Planned to be upgraded, but cancelled.
 * Farragut class destroyer (1958) - Planned, but only USS Mahan (DDG-42) was upgraded as a test platform in 1982.
 * Kidd class destroyer
 * Leahy class cruiser - All upgraded in the late-1980s and decommissioned by 1995.
 * Virginia class cruiser