A top U.S commander did not provide details, but the category of long-loitering, uncrewed aircraft includes fixed-wing aircraft, solar gliders and balloons.
Australia is planning its future military expansion as it seeks to fend off the widening influence of China and build its defense industrial capabilities.
The contractual milestone ends a four-year negotiating process with the F-35 Joint Program Office as the U.S. Air Force evaluates a replacement engine.