WASHINGTON — The Air Force has awarded Boeing a $2.3 billion contract for 15 more KC-46A Pegasus refueling tankers.

The award, announced by the Pentagon Tuesday evening, brings to 153 the number of KC-46s Boeing has on contract to build for the United States and allies. The Air Force plans to buy 179 KC-46s, and Boeing said it has so far delivered 76 of those.

The Japanese Air Self-Defense Force has two KC-46s in its fleet and four more on contract with Boeing, and Israel has ordered four of its own.

The Pentagon said work on these aircraft, which will be the KC-46′s tenth production lot, is expected to be complete by the end of July 2027. Boeing builds KC-46s at its factory in Everett, Washington.

This contract follows another issued in January for the ninth production lot, which was also for 15 tankers and valued at $2.3 billion.

The Air Force has steadily increased the presence of the KC-46 in its fleet and its abilities. In September 2022, the service cleared the KC-46 to refuel all aircraft, except the A-10 Warthog, and carry out all refueling missions around the world.

In July, Travis Air Force Base in California received its first of 24 planned KC-46s, which will replace the base’s aging KC-10 Extenders. Travis, the largest and furthest west of Air Mobility Command’s installations, is nicknamed the “Gateway to the Pacific” due to its location and status as a major hub for logistics and other mobility operations.

KC-46s also took part in July’s Mobility Guardian 23 exercise in the Indo-Pacific region, during which the tankers flew sorties of up to 35 hours straight. The service said in a release this showed the aircraft’s ability to carry out complex long-distance, long-duration missions to refuel fighters and other aircraft during operations.

And this fall, five KC-46s and about 12 service members from Joint Base McGuire-Dix-Lakehurst in New Jersey took part in a force generation certification event during the two-week Neptune Series exercise at Travis.

In addition to aerial refueling, the KC-46 can transport cargo, passengers and medical patients in aeromedical evacuation support missions, and can share data among other aircraft and ground operations centers to provide a fuller picture of the battlefield.

The Air Force awarded Boeing a $184 million contract in March to upgrade the KC-46′s communications systems with capabilities including antijamming and encryption features for its line-of-sight and beyond-line-of-sight communications technologies.

The Air Force also may buy an additional wave of 75 KC-46s as part of its planned recapitalization of its KC-135 fleet. Boeing’s chances of scoring that contract rose in October, when Lockheed Martin announced it would not compete for the interim tanker. But Airbus, which had partnered with Lockheed to jointly pitch their LMXT tanker, said it still plans to compete to replace the KC-135s.