New Threat Upgrade

New Threat Upgrade (NTU) was a United States Navy program to improve and modernize the capability of existing cruisers and destroyers equipped with Terrier and Tartar anti aircraft systems, keeping them in service longer.

Mahan 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. New Threat Upgrade allowed the full use of newer Standard missiles (SM 2ER BlkII w/Mk80 booster) and improved the interoperability of the radar, computer, tracking and engagement 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 the Aegis Combat System.

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. In 1988–90, the Kidd class destroyers received the New Threat Upgrade, including a new superstructure and heavier mainmast cooperative engagement with Aegis Ticonderoga class cruisers, which could control the Kidds’ surface to air missiles while they remained electronically silent. The Spruance class, the predecessor to and close relative of the Kidd class, did not receive the NTU.

The Cold War ended shortly after the New Threat Upgrade was initiated. The lower levels of funding available to the United States Navy after the Cold War meant that the NTU upgrade was never applied to all of the intended vessels. The NTU upgrade itself was expensive. Many of these ships were retired in the 1990s whether they received the full NTU modification or not; most of these warships built in the 1960s 1970s had high operational costs and manpower requirements (especially those which were nuclear powered), compared to newer Aegis warships. The USS Texas (CGN 39) was decommissioned during the upgrade, in the midst of her reactor refueling. USS Gridley (CG 21) received NTU in 1991 at a cost of $55 million but was decommissioned in early 1994. Overall, all US Navy ships that received the NTU upgrades were decommissioned within six years of their upgrade, as the Navy chose instead to order new ships with the Aegis weapon system. The Navy also accelerated the retirement of the Spruance and Kidd classes, despite their recent modifications, due to the arrival of the Aegis equipped Arleigh Burke class destroyers, which were more effective and cost efficient. The four Kidd destroyers were later transferred to Taiwan (Republic of China) where they remain in service, while some members of the Spruance class remained in service until 2005.

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