The Air Force has begun war games off the coast of Newcastle.
Exercise Diamond Shield is giving Air Warfare Instructors the most challenging test of their career - defending the east coast of Australia against "enemy" aircraft.
Dozens of RAAF aircraft are involved including F/A-18A, F/A-18F, E-7A Wedgetail, AP-3C Orion, C-130J Hercules and AAA Learjets.
United States F-16 Fighter jets have also flown across from Alaska to take part and will act as the "enemy".
"The F-16 is a different aircraft to what we operate in Australia (the F-18) which provides a different level of training for us," No. 88 Squadron leader wing commander Ray Simpson said.
"Their primary job is to simulate enemy aircraft."
F-16's in action over Williamtown (credit: Michael Douglas)
The exercise will take place about 40 kilometres off our coast between Newcastle and Coffs Harbour.
It'll run in waves of two, with six "friendly" aircraft against ten "enemy" aircraft at any particular time.
"It'll result in extra departures and arrivals at Williamtown, giving the public a chance to check out different aircraft," wing commander Simpson said.
The aircraft will take off at 9:45am and 2:15pm every day this week.
F-A 18 Hornet