Japan's defense chief says no sensitive data is known to have been lost in a cyberattack on the country's largest arms contractor.
Defense Minister Yasuo Ichikawa said Tuesday that he will instruct Mitsubishi Heavy Industries Ltd. to strengthen its data security systems.
The company says it is working with police and independent experts to investigate the attack. It says there was no confirmed leak of sensitive data involving its products or technology.
Japan's Nikkei business newspaper says the attack involved about 80 servers and computers at 11 facilities related to nuclear power, missiles and submarines.