As many as four C-17 Globemaster III airlifters, together with spare parts and associated equipment, are being sought by Australia from the United States.

The Boeing-made aircraft and other items requested would be procured through the U.S. Foreign Military Sales program and have a combined worth of an estimated $1.69 billion.

"Australia is an important ally and partner that contributes significantly to peacekeeping and humanitarian operations around the world," the U.S. Defense Security Cooperation Agency said in a notification to Congress.

"It is vital to the U.S. national interest to assist our ally in developing and maintaining a strong and ready self-defense capability. This proposed sale is consistent with those objectives and facilitates burden sharing with a key ally."

Australia currently operates six C-17A aircraft.

Included in Australia's shopping list: as many as four C-17A Globemaster IIIs; 19 F117-PW-100 Pratt & Whitney engines; Large Aircraft Infrared Countermeasures systems; Small Laser Transmitter Assemblies; AN/AAR-54 Missile Warning Sensors; Trimble Force 524 Receivers; GAS-1 antenna units; and Embedded Global Positioning System/Inertial Navigation Systems.

Spare and repair parts, supply and test equipment, and logistics and technical support services would also be part of the deal.