As the extent of Australia's military involvement in Iraq remains unclear, Greens Leader Christine Milne explains why Australia should join many other democracies in giving the national parliament the final say on whether we go to war.

The Abbott government, Labor opposition and Palmer Party have voted down the Greens bill to require that any decision to go to war be made by the parliament as a whole, not just by the executive.

"The Australian people, through the entire Australian Parliament, deserve a say in whether we go to war but Tony Abbott, Clive Palmer and the Labor party disagree," Greens Leader Christine Milne said.

As the situation in Iraq deteriorates, Australian Greens Leader Christine Milne wants to give Parliament the authority to debate and vote on any military deployments, and is calling for Labor's support.

"Unlike many other democratic countries, Australia's military can be deployed overseas without any discussion or decision in the Parliament. This must change," said Senator Milne.

With reports coming out of the United States of possible Australian military involvement in Iraq and Syria, Greens Leader Christine Milne says it is essential that any decision to deploy our military is brought to the parliament.

"It is essential that PM Abbott commits immediately to bring any debate about the deployment of Australian military to the parliament for debate," Greens Leader Christine Milne said.

Greens Leader Christine Milne has called on Prime Minister Tony Abbott and Opposition Leader Bill Shorten to rule out sending Australian troops to Iraq for a third war.

"Unilateral military action is exactly how Iraq got into this mess in the first place," Greens Leader Christine Milne said.

"Australia under John Howard blindly followed George W Bush into a very bloody conflict that was based on a lie. Tens of thousands of Iraqi civilians and thousands of coalition forces were killed. Killings and conflict continues to this day.