U.S. Air Force has awarded a contract to top aircraft maker Boeing Company (Boeing) on the sale of second KC-46 tanker to the Japan Air Self-Defense Force (JASDF), Boeing said on Monday.

The KC-46 military aerial refueling and strategic military transport aircraft is a multi-role tanker based on the Boeing 767 commercial passenger jet.

The deal, worth about 158 million U.S. dollars, was awarded by the U.S. Department of Defense last week through the Foreign Military Sale (FMS) program.

The manufacturing of the aircraft will be carried out in Seattle, Washington State on the U.S. west coast, and is expected to finish by June 30, 2021.

"Japan is our first KC-46 international partner and we look forward to delivering this highly capable, multi-role tanker to the JASDF," said John Suding, Asia regional executive at Boeing global sales and marketing.

The KC-46 Pegasus will be much easier to maintain than previous tankers, improving reliability and lowering life-cycle costs, Suding said, adding that it will be a valuable addition to Japan's air mobility fleet for decades to come.

Boeing said the first flight of the fully-provisioned KC-46 tanker took place in September 2015, and that six test aircraft have completed more than 3,700 flight hours and supplied over 4 million pounds of fuel to various U.S. military airplanes.

Boeing began developing the KC-46 tanker for the U.S. Air Force in 2011, and the 767-derivative aircraft is being assembled at its plant in Everett, Washington state.