C-17 production will end in 2015, Boeing announced. Denis Muilenburg, president and CEO of Boeing Defense, Space and Security, described the decision as “difficult but necessary.” Since production of the heavy airlifter for the U.S. Air Force began winding down some years ago, Boeing has extended the line every six months, based on signed or anticipated export orders.

Some of the 22 aircraft destined to be built are not yet sold. Current production is for India, which has ordered 10. Boeing built 223 C-17s for the USAF and has sold 39 for export to Australia, Canada, India, NATO’s Strategic Airlift Capability force, Qatar and the UAE, of which all but five have been delivered.

“Our customers around the world face tough budget environments. While the desire for the C-17’s capabilities is high, budgets cannot support additional purchases in the timing required to keep the production line open,” Muilenburg added.

Boeing said that nearly 3,000 employees support the C-17 program in four locations, including the final assembly line at Long Beach, Calif. Layoffs will begin early next year. More than 650 suppliers in 44 states contribute to the aircraft, according to Boeing.

Boeing said it will continue to provide after-delivery support of the worldwide C-17 fleet as part of the C-17 Globemaster III Integrated Sustainment Program (GISP) Performance-Based Logistics agreement. The GISP “virtual fleet” arrangement provides the highest airlift mission-capable rate at one of the lowest costs per flying hour, according to the company.

The C-17 line closure comes as three new airlifters are entering the market: the Airbus Military A400M; Embraer KC-390; and Indo-Russian MTA. Lockheed Martin continues to produce the C-130J, and Russia is modernizing the Ilyushin Il-76.