Terms of the transaction were not immediately available but Northrop said the acquisition would not be material to its 2014 financial outlook.
Qantas Defense Services, which serves government and military clients, is now known as Northrop Grumman Integrated Defense Services Pty Limited, part of Northrop Grumman Australia Pty Limited.
"Northrop Grumman IDS enhances our in-country footprint and local capabilities, and demonstrates our commitment to the Australian and regional defense markets," said Ian Irving, Northrop Grumman chief executive for Australia. "We expect this to be an important platform for international growth in our key focus areas of unmanned, cyber, C4ISR, and logistics and modernization."
C4ISR is the acronym for command, control, communications, computers, intelligence, surveillance and reconnaissance.
Additional details of the acquisition were not disclosed in the announcement of the takeover, which was released in the United States.