When Prime Minister Malcolm Turnbull gave a media conference at Holsworthy army base yesterday, the imagery was stark – a presentation draped in the trappings of militarism. Backed by the Chief of the Defence Force, Turnbull stood with masked and armed special forces soldiers from the 2nd Commando Regiment behind him. Just to underline matters, there was also a rather fearsome gunboat mounting a .50-calibre machine gun.

And you thought Tony Abbott liked to pose.

Ostensibly, Turnbull was announcing new counter-terrorism measures. The government will expand the cooperation between the Australian Defence Force (ADF) and domestic police agencies. There will be more training for police units from the army, and ‘more cooperation’.

Special forces soldiers will be allowed to go on ‘placements’ with police counter-terrorism units. The Defence Act will also be amended, allowing the states and territories to ask for help from the ADF more easily.

The new measures are the result of a review of the role of the ADF in domestic counter-terrorism. In part, they stem from the well-publicised failures of the New South Wales Police during the Lindt café siege in Sydney in 2014, where the ADF’s Tactical Assault Group was put on stand-by during the siege, but not ‘called out’ to assist by the New South Wales government.

Whether the ADF would have handled the Lindt cafe siege better than the New South Police did is a hypothetical question, but it has clearly spurred the government to tighten up the relationship between the states and territories and the Defence Force.

An expanded role for the special forces is not the only change in domestic security that the government is considering. Today the cabinet is meeting to consider whether to create a new ‘super-department’ along the lines of the British Home Office or the US Department of Homeland Security. The new portfolio would merge the Immigration department – already boasting its own paramilitary in the form of the Australian Border Force – with the Australian Federal Police and spy agency ASIO.

And Minister for Immigration and Border Protection Peter Dutton is the man who will oversee the new department.

Exactly why such a new portfolio is needed has not been explained by the government. The current arrangements seem to be working well enough, with cross-agency collaboration a feature of current government policy across many portfolios. Overseas spy agency ASIS sits inside Foreign Affairs, for instance, while domestic intelligence service ASIO currently resides in the Attorney-General’s Department. That doesn’t seem to stop the two agencies from cooperating where necessary, and from providing intelligence to other bodies like the ADF and the cabinet.

To take another example, the government’s vaunted boat turn-back policy, named Operation Sovereign Borders, is already a highly cooperative operation, structured as a ‘joint agency taskforce’ bringing in elements of the Navy, Federal Police, the Border Force and the Immigration department. Perhaps this is the model the government is considering. But if Operation Sovereign Border is already a joint success, what difference will a new minister make?

It is true, of course, that portfolio responsibilities change all the time. As anyone who’s ever worked in the public service can tell you, the constant churn of portfolios and responsibilities is a fact of life. Smaller agencies often find themselves shunted between various departments in a disruptive and often wasteful process known colloquially inside of the public service as MoG (short for ‘machinery of government’).

Sometimes the change is desultory – the old agency continues with a new big boss and a new logo and letterhead. But it can also create confusion and even chaos, as ‘silos’ are dynamited and middle managers are transferred or sacked. As the reshuffle comes into effect, units and sections must fight for a place in the new structure. Crippling turf wars can break out.

Intelligent observers, such as the ANU’s John Blaxland, tend to agree.  ‘I have yet to see any compelling evidence that what we have is not working, or that there is a compellingly better option out there,’ Blaxland told the ABC this morning. ‘Let’s just hasten slowly on this idea,’ he went on.

But it may be too late for that: the prime minister appears to have green-lit the changes this morning.

Now is the time for some pointed questions about what sort of powers the new ‘home minister’ will enjoy. As immigration minister, Peter Dutton already possesses wide and largely unfettered powers over asylum seekers and migrants under the Migration Act.

Adding the domestic spy agency and the federal police to his responsibilities creates even more opportunities for the arbitrary exercise of Commonwealth power.

As the minister responsible for ASIO, Dutton will be able to read pretty much every Australian’s phone and email metadata. As the minister in charge of the federal police, he gains responsibility for a force of 3,400 sworn police officers and the bulk of the Commonwealth’s counterterrorism investigations. As the minister in charge of immigration, Dutton will control citizenship, migration and who is let in and out of the country.

You don’t need to be paranoid to see the potential for abuse. There is a worrying concentration of power here. An ambitious and ruthless home minister will have all the resources required to suppress democracy and free expression, should he choose to: a spy agency, a police force, the border guards and a paramilitary.

Such abuses may not seem likely in twenty-first-century Australia, but they are certainly not inconceivable. The federal police have already accessed Guardian journalist Paul Farrell’s email data in an attempt to hunt down his sources … without a warrant. The Immigration Department has unlawfully detained Australian citizens on Christmas Island.

Australia is not currently an unfree society. But we have put in place a system of widespread government surveillance, and we have legislated away many of the rights of non-citizens, such as those interned on Manus Island and Nauru. Further concentrating power in the hands of a single minister is another slide down an already slippery slope.

Image: Turnbull presser screen shot / Ben Eltham