TOKYO: Japan plans to hold talks with the United States over contracts worth 178.7 billion yen that have already been concluded for the deployment of the Aegis Ashore land-based missile defense system, informed sources said Thursday.

But the negotiations would be tough as Washington is likely to take a stern attitude toward Tokyo, which abruptly announced Monday its decision to freeze plans to deploy an Aegis Ashore unit in the northeastern Japan prefecture of Akita and another in the western prefecture of Yamaguchi.

According to the sources, Japan's Defense Ministry has estimated the total costs at 450.4 billion yen, including 126 billion yen per unit for the deployment of the system and expenditures for training and maintenance.

Of the total, deals worth 178.7 billion yen have so far been done, with 12.5 billion yen already paid to acquire information on the Aegis system. Besides, the ministry has disbursed 6.5 billion yen under a 35-billion-yen contract to purchase high-performance SPY-7 radars for the missile defense system.

Japan can terminate the Aegis Ashore contracts under the terms of the U.S. Foreign Military Sales program but is required to shoulder costs stemming from the cancellation.

How much Japan should pay will be determined by the envisaged negotiations with the United States, a ministry official said.

Meanwhile, the ministry will study if the radars can be mounted on the Maritime Self-Defense Force's Aegis destroyers, people familiar with the matter said.

Defense Minister Taro Kono said Tuesday that enhancing Aegis ships' capabilities to detect and shoot down enemy missiles would be an option.

JIJI Press