IS no longer has the initiative in Iraq

The expansion of Australian and French air strikes in Syria has increased the vulnerability of Islamic State forces in the Middle East, a senior military commander says.

As well, the Iraqi government with coalition support now dictated the pace of operations across much of its territory despite occasional setbacks, Defence force chief of joint operations David Johnston said.

"Daesh no longer owns the operational initiative that we had seen it possess a year ago," the vice admiral told reporters in Canberra on Wednesday.