The first Boeing KC-46A tanker built for the Japan Air Self-Defense Force recently refueled another KC-46A aircraft.

It is the first non-US KC-46A to do so. During the test flight, the aircraft also received fuel in return.

“Refueling with the first Japan KC-46A is an important milestone for the Japan Air Self-Defense Force,” said Jamie Burgess, KC-46 program manager. “KC-46A is the world’s most advanced air refueling aircraft and has already transferred more than 42 million gallons of fuel to other aircraft globally through its boom and drogue systems.”

Boeing was awarded a Foreign Military Sale contract from Japan for one KC-46A aircraft and logistics services in December 2017. The U.S. Air Force exercised an option for Japan’s second aircraft on December 10, 2018.

The KC-46 will join the four KC-767J tankers of the JASDF 404th Tactical Airlift Tanker Squadron which operates from Komaki Air Base. It will be able to service Japan’s fleet of F-15J/DJ Eagle fighter jets as well as its newly acquired Lockheed Martin F-35A/B Lightning II fighters.

The KC-46A is a multirole tanker supposed to refuel all allied and coalition military aircraft compatible with international aerial refueling procedures and can carry passengers, cargo, and patients. But the aircraft has encountered numerous technical problems since its delivery, including three “critical deficiencies” that could take years to fix.