The U.S. Defense Department is actively courting private-sector Japanese companies whose civilian technologies have military applications and is particularly interested in 16 categories, a U.S. official said.

The official told Kyodo News the Pentagon has explored using Japanese nuclear protective covers, batteries and photovoltaics among other technologies since 1980. The official did not clarify whether the U.S. actually used any of the technologies for military purposes.

In 2014, when Japan loosened long-held principles and guidelines on arms exports, the U.S. Defense Department held a seminar to solicit cooperation from Japanese firms in developing militarily useful technologies and equipment. The meeting was arranged by the Ministry of Economy, Trade and Industry, the official said.

The Pentagon held another seminar last year in Tokyo to explain the procedures required to become research partners and suppliers for the U.S. military. Of particular interest was Japanese energy-conservation and materials technologies.

With Tokyo trying to strengthen security ties with Washington under Prime Minister Shinzo Abe's conservative government, Washington has become more active pursuing state-of-the-art technologies developed in Japan.