In anti-budget rallies, protesters have loudly demanded the government spend more money on health, welfare and education and not $12 billion on new jet fighters.
So how does RAAF chief Air Marshal Geoff Brown respond to that one?
'Security is one of the fundamental responsibilities of government. The unfortunate thing with defence is that the debt that you actually owe the future needs to be paid today,' he said.
Addressing a dinner of the air power think tank the Williams Foundation, he said the F-35 Joint Strike Fighter was a 30-40 years investment in capability.
