Australia was opening its first parliamentary debate on Tuesday on its nine-year military deployment in Afghanistan, after fractures appeared in the national commitment to the war, its strategy and objectives.

The three-day debate was unlikely to lead to any major policy change, because the major political parties have expressed their determination to stay the distance with the United States, Australia's most important military ally.

Prime Minister Julia Gillard succumbed to pressure from the anti-war Greens party by agreeing to the parliamentary debate on Australia's commitment of 1,550 troops to the conflict. Gillard relies on support from the Greens to rule since August elections gave no party a parliamentary majority.

It will be the first such debate on the Afghan deployment. In Australia the Cabinet commits the nation to war without any need to consult the parliament.

Gillard and opposition leader Tony Abbott both indicated that they would use their speeches Tuesday to maintain bipartisan support for the Australian mission in southern Uruzgan province, where Australian soldiers train an Afghan army battalion to take charge of provincial security. That mission is expected to take between two and four years.

But a lawmaker in Abbott's Liberal Party, Mal Washer, and newly elected independent lawmaker, Andrew Wilkie, have announced that they agree with the Greens that Australian troops should be withdrawn.

Foreign Minister Stephen Smith said the US-led coalition had made a mistake in becoming distracted by the Iraq war and had taken too long to find the right strategy in Afghanistan. Smith's Labor Party was not in power when Australian supported the 2003 Iraq invasion.

"It's not just a military strategy. It's a military and political strategy," Smith told Australian Broadcasting Corp. radio.

A dozen members of group representing veterans and former service personnel opposed to both the Afghanistan and Iraq demonstrated outside Parliament House on Tuesday before the debate.

"In the history of Australia at war, this in an important day - a war is being reviewed," the group Stand Fast's spokesman Graeme Dunstan said.

Greens leader Bob Brown said most Australians now agreed that their troops should be withdrawn.

"Things are changing rapidly in Afghanistan, and I'm concerned about the lives and safety of Australian troops," Brown told ABC.

Neil James, executive director of the independent security think tank Australian Defense Association, which argues for more Australian troops in Afghanistan, said he did not expect the parliamentary debate would result any major policy shift.

"Our big hope is that the wider general public debate will become more informed," James said. "The public debate has become reasonably uninformed and very emotional because governments of both political persuasions haven't led the debate well enough."