Liberal Democratic Party policy chief Shigeru Ishiba says the Self-Defense Forces should develop a unit equivalent to the U.S. Marine Corps so it can mount amphibious operations to take back islands invaded by foreign troops.

"I think it's strange for an island country like Japan not to have marines in the future," said Ishiba, who was defense minister in a previous LDP-led government.

Prime Minister Yukio Hatoyama said Sunday it is necessary to maintain the deterrent provided by U.S. forces in Japan, including Okinawa-based marines, at a time when uncertainties remain over regional security. That deterrence is the main reason he cited in his decision to keep the U.S. Marines' contentious Futenma air station in Okinawa.

"Isn't there anything Japan can do at a time when it has made the United States (provide Marine functions)?" Ishiba said Sunday on Fuji TV, adding it would be possible for an SDF marine unit and the U.S. Marines on Okinawa to operate together.