TOKYO — Japan has approved the export of a locally-made component for a missile defense system to the U.S. and is launching joint research with Britain on air-to-air missile technology for fighter jets.The approval late Thursday marks the first defense technology transfer since Japan eased military export rules in April.The policy change reverses Japan's 1967 self-imposed ban on arms exports under its war-renouncing constitution. It comes as Prime Minister Shinzo Abe's government wants to give Japan a more assertive defense posture.Under the approval, made by the National Security Council, Japan's major defense contractor Mitsubishi Heavy Industries Ltd. can export seeker gyro, a component for Patriot Defense Capability-2 surface-to-air missile defense system, to a U.S. defense equipment maker Raytheon Co. The gyro is a sensor in the missile to identify, track and chase targets.Mitsubishi Heavy has been licensed to produce seeker gyros for Raytheon, which stopped producing them itself. The U.S. requested the export, and Mitsubishi-made seeker gyros would be transferred to Qatar, officials said. Japan's government said the export is primarily to a licensee in the U.S., Japan's top ally. But the U.S. has exported PAC-2 to nearly a dozen countries including Israel.Separately, the government also gave a green light to Japan's joint research with Britain using Japanese seeker technology. It's a simulation-based project linked to a Meteor missile development among European countries. Defense Ministry official Toru Hotchi said Japanese officials are hoping the research can lead to a technology that can be used for F-35 stealth fighter jets that Japan plans to purchase for its Air Self-Defense Forces.Mitsubishi Electric, which also supplies missile parts for Japan's Self-Defense Forces with renowned sensor technology, is a top candidate to participate in the project, aimed at strengthening security and defense cooperation between Japan and Britain, while contributing to Japanese military capability, officials said."It would not only strengthen national security and defense cooperation between Japan and Britain, but also could contribute to raise the capability of (Japan's) Self-Defense Forces in the future," according to a government statement jointly issued by foreign, defense and industry ministries.The U.S. is supposed to build nearly 2,500 of the F-35 jets. Nine partner countries, including the U.K., Denmark and Italy, are involved in the plane's production.