The commitment to purchase the aircraft, under development for the U.S. Navy, was made in a statement issued this week from the office of Australian Prime Minister Tony Abbott.
The MQ-4C Triton is a maritime surveillance platform with a maximum speed of 357 miles per hour, a service ceiling of 60,000 feet and an endurance of 30 hours. It is intended to complement maritime patrol aircraft.
"These aircraft will patrol Australia's vast ocean approaches, and work closely with other existing and future Australian Defense Force assets to secure our ocean resources, including energy resources off northern Australia, and help to protect our borders," the Prime Minister's office said.
Acquisition of the aircraft and their ground stations will require about $125.5 million of new facilities and infrastructure. About $89.6 million would be invested in the state of South Australia, where the UAVs would be based.
The statement said the number of Triton UAVs to be procured would be decided in 2016.