Peter Dutton insists Australia's intelligence and security agencies fully support the creation of a new mega-portfolio under his reign.
And the soon-to-be Home Affairs minister dismissed as "juvenile" claims by Labor it's merely a move to shore up his support for Malcolm Turnbull.
The prime minister on Tuesday dubbed the restructure the most significant of its kind in four decades as Australia tried to stay ahead of the threats it faced.
"It is not about politics. It is about safety, Australians' public safety," he told reporters in Canberra.
"The arrangements that I have announced are ... logical, they are rational, they make operational sense."
They would also give Mr Dutton responsibility for the agencies "defending, preserving, protecting our national security at home".
The portfolio, modelled on the UK's Home Office, not the Department of Homeland Security in the US, will include domestic spy agency ASIO, the Australian Federal Police, the Australian Border Force and the Australian Criminal Intelligence Commission.
Mr Dutton, who now holds the immigration and border protection portfolio, will be assisted by Attorney-General George Brandis and Justice Minister Michael Keenan.
The transition will be managed by a taskforce and be completed by mid-2018.
Mr Turnbull says the changes follow a review of Australia's intelligence community by Michael L'Estrange, a former head of the foreign affairs department.
But he conceded a home affairs ministry wasn't a specific recommendation as the idea wasn't within the review's remit.
"We need these reforms, not because the system is broken, but because our security environment is evolving quickly," he said.
Mr Dutton refused to say whether the AFP or ASIO asked for the changes, questioning why anyone would not want an arrangement with greater collaboration and sharing of information.
"I believe the agencies support very strongly the announcement," he told ABC's 7.30 program.
"The intent of the government is to do whatever we can to make Australians safe."
Labor will be briefed on the L'Estrange review and the government's announcements.
Opposition Leader Bill Shorten warned the idea was more about resolving Liberal party civil wars than developing a national anti-terrorism strategy.
"I don't think this is a captain's call. I think it's Peter Dutton's call," he told reporters in Sydney.
"Everybody knows that Malcolm Turnbull has to keep Peter Dutton onside so Malcolm Turnbull can keep his own job."
Mr Dutton labelled it a juvenile statement.
Former ASIO boss Dennis Richardson said it was "difficult to criticise, but equally I think it's difficult to proclaim it as some great advance forward".
He questioned whether a minister other than the attorney-general should be able to authorise warrants.
There were some "marginal benefits" in bringing the immigration portfolio under the national security umbrella, he told a Lowy Institute forum in Sydney on Tuesday.
"I think there is a reasonable argument in respect of immigration and bringing immigration closely together, but beyond that it is primarily presentational."
In other changes, an office of national intelligence will be established and the Australian Signals Directorate - defence's intelligence agency - will become a statutory authority.
Cyber security arrangements will be bolstered with Mr Turnbull's cyber security special advisor to head the Australian Cyber Security Centre.
