TOKYO - Japan and the United States began the final discussion over Japan's purchase of four units of the F-35 stealth fighter on Wednesday, and the two governments may sign the contract next month reported by the local media.

The Japanese government decided to choose the F-35 stealth jet, developed by the US and eight other countries, as the country's next-generation fighter jet last December.

If the tow sides could reach the agreement smoothly, the aircrafts will be delivered in fiscal 2016 to Japan by the US government.

But the Japanese Defense Minister Naoki Tanaka said in February if Japan's requirements, including performance and cost, are not satisfied, the ministry will consider canceling the contract or picking other aircraft.

Japan plans to eventually have total 42 units of the F-35 jet, but the unit price was unrevealed.