text: The  of guided-missile destroyers in the Japan Maritime Self-Defense Force are equipped with the Aegis Combat System, and is the first of few ship classes outside the United States to have that capability. Following a decision made in December 2003, Japan is upgrading their Kongo-class destroyers with Aegis Ballistic Missile Defense System. The upgrade involves a series of installations and flight tests to take place from 2007 to 2010. JS Kongo was the first ship to have the BMD upgrade installed.
  Background
  The JMSDF built  under FY1960 program and started shipboard operation of surface-to-air missiles. She had been equipped with analog-version of the Tartar Guided Missile Fire Control System. A fully-digitized system was adopted on the next-generation , and later a combat direction system based on the Naval Tactical Data System was added.
  Nevertheless, the JMSDF estimated that its fleets would not survive against Soviet airstrikes, especially Tupolev Tu-22M bombers and AS-4 air-to-surface missiles. Based on these estimates, JMSDF began to pursue the introduction of the Aegis Weapon System (AWS) from the early 1980s. In 1984, with the prospect of deploying AWS, concrete implementation plans began. And the construction of Japanese first Aegis-equipped ships, Kongo class, had begun under the FY1988 program.
  Design
  The overall design is generally modeled on the s of the U.S. Navy. The hull adopted shelter deck design as with preceding Japanese destroyers, but it was widened to support the superstructure with four PESA antennas just as Arleigh Burke class. Due to this widened hull, the outer panel is inclined to reduce the width of the waterline, which also has the effect of reducing radar cross section area.