Northrop works with its partners to supply airframe parts and accessories for its early warning E-2C aircraft, with options to increase support as needed.
"Japan is our largest international Hawkeye operator," Bart LaGrone, vice president of E-2/C-2 programs at Northrop Grumman Aerospace Systems, said.
"The demand for E-2 Hawkeye airborne early warning and control is even greater now than when the systems were first delivered to Japan Air Self Defense Force in 1984," he said.
AAR is an international aviation distribution and logistics business based in Wood Dale, Ill. Sumitomo is a resources and commodities trading business based in Tokyo.
Japan acquired its E-2C fleet initially to provide over-the-horizon early warning against low-flying aircraft. Japan's high-wing twin turbo-prop fleet has 115,000 accident-free flight hours.
"Northrop Grumman will continue to provide E-2C support to JASDF and other E-2C operators as the U.S. Navy begins its transition to the E-2D advanced Hawkeye in fiscal year 2015," LaGrone said.
Northrop's other industry partners for Japan's Hawkeye fleet include Toshiba Corp. and Kawasaki Heavy Industries.
Grumman Corp. -- later Northrop Grumman -- began producing the Hawkeye in 1964 for the U.S. Navy as a replacement for Navy's snub-nose radial piston E-1 Tracer, also made by Grumman.
The Tracer, the Navy's first purpose-built airborne early warning aircraft, entered service in 1958. It was replaced by the more modern E-2 Hawkeye in the early 1970s.
Taiwan also operates Hawkeye aircraft, purchasing four E-2T variants in late 1995.
The Taiwan government sent two of them back to the United States in 2010 for upgrading to E-2K standard. The other two were sent back for upgrading and returned last year, Focus Taiwan newschannel reported.
Singapore had four Hawkeye aircraft, but phased them out in favor of the early warning variant of the twin jet engine Gulfstream G550.
Singapore took delivery of its General Dynamics Gulfstreams, powered by two Rolls Royce BR710C4-11 turbofan engines, from 2009 to 2011.
Northrop announced in October it had picked up a $34.5 million contract from the U.S. Navy to upgrade the French navy's fleet of three E-2C Hawkeyes with an upgraded friend-or-foe identification system.
The system will increase commonality and interoperability between the French fleet and the U.S. Navy's E-2D Advanced Hawkeye aircraft, Northrop said in a written statement.
The French Navy has operated its fleet since 2000 and is the only military other than the U.S. Navy to operate its Hawkeyes from an aircraft carrier.
The first U.S.-France carrier-to-carrier flight was in May 2001 when a U.S. Navy Hawkeye flew from the deck of the USS Enterprise to the deck of the French carrier Charles de Gaulle.