Australian Greens Leader Christine Milne says Tony Abbott has sent Australians to another war in Iraq with a claim that following the United States is in our national interest.

"The Greens stand with those Australians who are asking why is it in Australia's national interest to join in a another war in the Middle East without a clear strategic objective or risk assessment?" Senator Milne said.

"How will this war make us safer? Won't it make us a bigger terrorism target and a more attractive recruiting ground for jihadists?

Greens Leader Christine Milne has called on Australians to stand together against terrorism threats on home soil, saying unity, not war, will deliver lasting peace.

"The best way to keep Australians safe is to bring them together, not blindly follow the US into an unwinnable war in the Middle East," said Senator Milne.

"Are we going to another war in the Middle East because the terror alert has been raised, or the other way around?

Australian Greens Leader Christine Milne says Tony Abbott should level with the men and women of Australia's Defence Force when he farewells them tomorrow on an open-ended mission to Iraq.

"When you ask young men and women to put their lives on the line, you should be honest enough to tell them that you're committing them to war," said Senator Milne.

"This has been mission creep from the start. Australia is getting itself into an open-ended war.

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.