1 Washington has asked Tokyo to provide scientific information about an improved type of wing developed for Japan's latest jet fighter, which is based on the U.S.-made F-16, officials said Tuesday.
2 'The issue has been discussed for some time between authorities concerned from both sides,' said Japanese Defense Agency spokesman Takahiro Goto.
3 Goto said the technology developed by Japan's Mitsubishi Heavy Industries involves a composite material from carbon fiber that enables production of a wing that is lighter, wider and stronger.
4 Under a 1988 agreement on the joint development of the FSX fighter, both sides are obliged to provide the other side with any 'derivative' technology, Goto explained.
5 U.S. and Japanese officials have yet to determine if the Mitsubishi technology is its own or derivative, he added.
6 Last month, Japan rolled out the first prototype of its FSX fighter. The unveiling was two years later than originally planned because of delays caused by often tense negotiations with Washington.
7 Japan initially had planned to develop a fighter on its own, but after pressure from Washington agreed in 1988 to jointly develop the FSX fighter.
8 Under the deal Mitsubishi and Lockheed Corp. shared technology, with the Japanese learning basics of the F-16 and the Americans learning advanced materials and radar technology.
9 Tokyo and Washington will still have to decide on how many of the jet fighters to make. Japan is likely to want only about 80, but the United States wants to sell as many as 130, Japanese news reports have said.
10 The price of the FSX, scheduled to make its maiden flight some time next summer, has yet to be set.
11 The Japanese air force hopes that the new fighters will be ready for full use by the end of the decade.
12 The Japanese FSX fighters will be harder to track by enemy radar and will have improved ability to hit targets. Also, the fighter's size is larger without adding a proportional amount in weight.

Washington has asked Tokyo to provide scientific information about an improved type of wing developed for Japan ' s latest jet fighter , which is based on the U . S . - made F - 16 , officials said Tuesday .
provide scientific information
Scientific information about what?