Prime Minister Malcolm Turnbull has adopted blunt language to describe the fight against the Islamic State group, declaring Australia is "killing terrorists" in the Middle East.

The frank assessment came as Mr Turnbull marked the arrival of the first Joint Strike Fighter in Australia and outlined the Federal Government's determination to "destroy" terrorist enemies, especially those in Iraq and Syria.

"Our job is to protect Australia from all threats. Right now, as you know, our Air Force is operating in the Middle East killing terrorists," Mr Turnbull said.

Mr Turnbull pointed to laws passed by the Federal Parliament last year that allow the Defence Force to target more Islamic State fighters in Iraq and Syria.

He said before the law was changed, Defence personnel "could only target terrorists when they were actively engaged in combat".

"We weren't able to target them when they were in support roles, in logistics, planning, in financing for example," Mr Turnbull said.

"My Government changed the law so that our Australian Defence Force is able to kill terrorists in the Middle East whether they have a gun in their hand, a bomb in their hand, whether they are in the back office planning an attack or raising money or engaged in logistics."

Mr Turnbull's predecessor Tony Abbott used notably hawkish language when it came to tackling terrorism, describing IS as a "death cult".

Today, Mr Turnbull also used candid language about the conflict.

"This is a struggle where we are determined to destroy the enemies, the terrorist enemies we face in the Middle East," he said.

"Our men and women are doing that, they're doing that together with our allies, the United States and others, we're doing that successfully, we are destroying Daesh in the field and their so-called caliphate is coming to an end."