Defense Minister Itsunori Onodera said Friday his ministry is studying whether F-35B fighter jets can be deployed on Maritime Self-Defense Force helicopter carriers, a move likely to be viewed as yet another signal Japan is retreating from its strictly defense-oriented military posture.

Under the postwar Constitution, the government has maintained it cannot possess "attack aircraft carriers" because they are could be deemed offensive weapons exceeding the "minimum force" needed for Japan to protect itself.

Japan has flat-topped destroyers that carry helicopters, but not fighter aircraft.

Onodera emphasized at a Diet committee that the study involving the helicopter carrier Izumo, Japan's largest naval vessel, is being conducted for the purpose of "basic information gathering" and not "on a premise that F-35Bs will be introduced."

Prime Minister Shinzo Abe, who was attending the committee meeting, supported the study.

"It is a matter of course that we study what possibilities can be foreseen in dealing with crises and constantly consider (what we need)," Abe said.

The MSDF's Izumo-class carriers are 248 meters long and can carry up to 14 helicopters. The F-35B is the U.S. Marine Corps variant of the F-35 Lightning, a next-generation stealth jet made by Lockheed Martin Corp. They are capable of making short takeoffs and vertical landings.