The Japanese government may consider selling some of its aging F-15J fighter jets back to the United States, the Nikkei reported on Monday.

According to a media report, Japan is considering selling its F-15Js the U.S. to raise funds for purchases of advanced F-35 Lightning II stealth aircraft. Also noted that Washington may sell those fighters to South East Asian nations at cheap prices.

Several Japanese officials have confirmed that discussions are underway for what would be the nation’s first sale of used defense equipment to the U.S. Tokyo sounded out Washington on the possibility of such a sale as part of negotiations to purchase 105 F-35 jets from the U.S. The two sides are trying to iron out such details as the number of F-15s to be sold and their prices.

Japan plans to buy 45 Lockheed Martin Corp F-35 stealth fighters, worth about $4 billion, in addition to the 42 jets already on order, according to a separate five-year procurement plan.

The new planes will include 18 short take off and vertical landing “B” variants of the F-35 that planners want to deploy on Japanese islands along the edge of the East China Sea.

As to F-15J, it is an all-weather air superiority fighter based on the McDonnell Douglas F-15 Eagle in use by the Japan Air Self-Defense Force (JASDF). The F-15J was produced under license by Mitsubishi Heavy Industries.

Japan’s roughly 200 F-15J s form the core of the Air Self-Defense Force’s air defense capabilities.