Former Australian Army chief Peter Leahy wants a rethink of Defence policy, saying military intervention is not the only way to achieve peace.

Professor Leahy says Australia should reconsider its spending on defence hardware like the Joint Strike Fighters, suggesting it buys only 50 of the jets from the United States instead of 100.

He says there should also be a greater focus on non-military strategies and aid programs.

"When I look at current deployments ... 10 years in East Timor, 10 years in Afghanistan, we've been in the Solomon Islands for a long time and we were in Iraq for a long time and so, why is it taking so long?" he said.

"Can we have an alternate strategy, in some way, that's almost an exit strategy for the military?"