As the parliamentary year enters its final week, there is chatter about whether Mr Turnbull could move - most likely in the new year - to refresh his frontbench.

Former prime minister Tony Abbott on Sunday gave a wide-ranging interview that included policy and budget advice for the government, and signalled his desire to return to the frontbench.

Defence Minister Marise Payne - who is currently on leave and recovering from surgery - veteran Indigenous Affairs minister Nigel Scullion and accident-prone Attorney-General George Brandis have all been mentioned as possibilities for a shift.

Senator Brandis has been under pressure over the Bell Group legal dispute, and on a range of other fronts.

Labor defence spokesman Richard Marles and Australian Strategic Policy Institute chief Peter Jennings have called for the responsibilities of Senator Payne and Christopher Pyne to be clarified.

The pair also raised concerns the Turnbull government let the annual US-Australian AUSMIN talks, which bring together the two nations' defence and foreign affairs ministers and which were due to take place earlier this month, to fall by the wayside.

Senator Payne and Mr Pyne are both in cabinet and serve as Defence and Defence Industry Minister respectively.

When Mr Turnbull announced the arrangement, he said it was necessary given the massive $195 billion investment in Defence procurement over the coming decades.

Asked about his frontbench on Tuesday morning, Mr Turnbull said "this is a ritual question. Look at my frontbench and what they have delivered. Look at the cabinet, what they have delivered" and pointed to the passage of the Registered Organisations union bill, CFA legislation, omnibus savings bill and superannuation changes.

"I have an excellent ministry. I am delighted with the work that my colleagues are undertaking, it is measured by results. The results are building up and we are delivering."

There are however questions in the Coalition and in the broader defence community about division of roles between Mr Pyne and Ms Payne, and concerns about Senator Payne's office.

Some have likened Senator Payne's office to that of former prime minister Kevin Rudd - bureaucrats would wait until Mr Rudd was overseas so they could submit documents to then-deputy prime minister Julia Gillard's office for more rapid approval.

Senator Payne is notionally the senior minister, though Mr Pyne outranks her in the cabinet pecking order.

Mr Marles told Fairfax Media the government had "failed to properly articulate to the public how the two defence ministers work, in relation to each other".

"I think it is certainly confusing to the Australian public how the two defence ministers operate, that's why Labor has maintained the traditional structure in terms of the defence portfolio," he said.

Mr Jennings, a former Defence Department deputy secretary, said "I think more clarity is needed about the division of responsibilities, in particular for industry and the department. Anything that could reduce double handling would be a sensible step".

Mr Marles said that with Donald Trump due to replace Barack Obama in January 2017, and new appointments as Secretary of State and Defence Secretary, the annual AUSMIN talks - even though they would have been led by Obama administration officials - could have served as a sort-of incoming government brief for US State Department and Defence bureaucrats.

"With any new administration, there are a lot of issues which need clarification within the context of the alliance. That would have been the case if Hillary Clinton had been elected and it is clearly the case in terms of the incoming Trump administration," he said.

"In that context it is very concerning that AUSMIN has not occurred this year,this is the premier forum where the issues within the alliance are ventilated, it has happened in previous US election years, it happened in 2012, it happened in 2008."

Mr Jennings said the government "should have pushed harder" for AUSMIN to be held.

Although the talks were due to be held in Sydney this year, "we should have been willing to meet them in the States". This is a reference to the offer of a two-hour meeting in Washington, rather than the usual full-day meeting and dinner, made by the US which Australia rejected.

In a statement, Foreign Minister Julie Bishop said that "despite our best efforts to find a suitable date, including offering to travel to the USA, we could not co-ordinate the schedules of four ministers".

"In the meantime Minister Payne and I have met with our USA counterparts on a number of occasions this year. The government will be engaging the Trump Administration once it enters office to set a date for AUSMIN in 2017."

Comment has been sought from Senator Payne.

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