Since the conclusion of World War 2, Australia has been a staunch supporter and ally of the Unites States of America, supporting them in many military actions over the last 70 years.
Military alliances and support are mutually beneficial for nations involved in deterring aggressors and securing national interest of countries that participate in said partnerships.
The issue however is, for the last 50 years the United States and its allies (including Australia), have become the aggressors.
Our troops and nation’s resources have been called upon multiple times over the last few decades with the use of carefully planned and calculated lies, that instill fear into the population for the sole purpose of manufacturing consent to support military actions around the globe.
Some key unjustified Australian military actions over the last 50 years include Vietnam, Iraq and Syria.
The Vietnam war was sold to the Australian people as a war to protect western freedoms from the expanding communist sphere of influence.
Prime Minister Menzies was quoted at the time saying:
“The takeover of South Vietnam would be a direct military threat to Australia and all the countries of South and South-East Asia. It must be seen as a part of a thrust by Communist China between the Indian and Pacific Oceans.” 
From 1962 to 1972 this lie was to cost Australia 500 troops with over 3000 wounded in a military conflict that saw 61,000 Australian troops deployed in Vietnam. 
The war that we could not afford to lose, according to our leaders, was lost.
All the doom and gloom that was projected on the Australian people did not come to fruition.
Communism did not dominate the freedoms of the West and the world did not fall into chaos as predicted by our leaders, should we fail.
It is perhaps ironic that today Communist China is Australia’s largest economic trading partner.
It would be some time before Australia was to deploy troops to an international conflict under the pretext of lies, but in 2003 Prime Minister John Howard decided to commit Australian troops to invading Iraq (again) under US leadership. The goal was to remove the Saddam government from power.
(The first Gulf war in 1991 did see Australian involvement but it was largely an non combat role from some navy elements)
During John Howard’s speech to parliament on Feb 4 2003, “Weapons of Mass destruction”, was referenced 16 times and a driving factor for Australia’s motivation for going to war was as quoted by Prime Minister Howard :
“The ultimate nightmare for us all must be that weapons of mass destruction fall into the hands of terrorists.” 
The threat of collusion between Al-Qaeda and the Saddam government to arm terrorist with WMDs, was sold to the Australian public while the events of 9/11 and the Bali bombings were still fresh in the minds of many fearful citizens.
Put aside the fact that military action was not sanctioned by the UN, as well as the fact that Saddam and Iraq had nothing to do with both the above hideous actions, WMD’s did not exist in Iraq. Furthermore Saddam was a staunch opponent of Al-Qaeda within his own boarders contrary to what Prime Minister Howard claimed. 
The result of the war was in fact the opposite of the objective. The war not only destabilised the region it also ended up providing the perfect environment and conditions for terror organisations to grow and recruit in the power vacuum created.
The financial costs of these lies for the Australian tax payer have been astronomical.
Costs not only include military expenditure but costs to house and sustain refugees fleeing the destabilised area  as well medical costs for veterans that are dealing with PTSD and injuries sustained in the course of the wars.
Australia’s involvement in Syria is really just a continuation of the Iraq war in the aftermath of a destabilised region which our US allies have then used to try and overthrow the Assad government (much as we had done to Saddam).
Australia’s involvement in Syria has been justified to the Australian people, as a fight not aimed at the Syrian government, but to counter ISIS and other Islamic extremist groups within the country and northern Iraq.
This is in clear contradiction of our allies goals, who Australian forces are commanded by.
The US, UK, Turkey and it key Gulf allies have directly funded and aided the opposition of the Assad government including Al-Qaeda and ISIS.
How can we be fighting against these terror organisations when we fall under the command of the powers that have directly aided them?
It is a contradiction of objectives.
The Syrian/Iraq conflict is costing Australian taxpayers $1 billion annually in direct military spending  and an additional $700 million for supporting refugees coming from Syria .
The cost of these conflicts do not even include the wasteful deaths of innocent civilians, many of which are children in the war zones.
We are now being told in recent weeks that North Korea poses an imminent threat to Australia. We are told they have capabilities and motivation to reach Darwin with a potential nuclear strike. 
We are not saying we should not takes issues of our national security seriously.
North Korea is a potential danger to the SE Asian region, but once again we are being manoeuvred by fear into a position that can see Australian troops support US forces in a war that can be avoided with diplomacy.
If we have not learned anything from Vietnam, Iraq and Syria then we are doomed to be herded like sheep by our governments into aggressive conflicts and perpetual warfare that can be avoided.
 http://www.iraqinquiry.org.uk/media/247921/the-report-of-the-iraq-inquiry_executive-summary.pdf (page 43 )