The United States has asked Tokyo to pay around ¥1 billion for information on the capabilities of the stealthy F-35, a leading candidate to replace Japan's aging fighter-jet fleet, sources said Saturday.
It is rare for a country to be charged such a large sum for information on potential imports of defense equipment.
The U.S. also told Japan that Washington will not provide information on the F-35's radar-evading capabilities until Tokyo makes a decision to purchase it, the sources said.
Defense Minister Toshimi Kitazawa and U.S. Defense Secretary Robert Gates will likely discuss the deal when they meet in Japan on Oct. 20.
Japan had initially hoped to procure the F-22 stealth fighter, but Washinton banned its export and announced it was ending production.