Australia on Monday swore in its first female defence minister, Senator Marise Payne, who will oversee open-ended military engagements in two countries and some of the country's most important defence contracts in a generation.

Prime Minister Malcolm Turnbull last week ousted long-time rival Tony Abbott as leader of their ruling Liberal Party, citing a chaotic management style and dismal poll numbers.

Turnbull's cabinet which was sworn in on Monday features five women, more than double the previous number.

In a symbolic break from the past, Turnbull jettisoned several ministers seen as close to aging former Liberal Party prime minister John Howard.

Payne, most recently human services minister and a former chair of parliament's foreign affairs, defence and trade committee, as well as its human rights subcommittee, replaces Kevin Andrews after less than a year in defence.

Defence has been a revolving door portfolio over the past five years and badly needs stability as it sets about reforming a bureaucratic procurement pipeline, said Andrew Davies, director of research at the Australian Strategic Policy Institute.

Abbott centralised decision making in his office and locked his defence ministers out of major decisions such as choosing the A$50 billion ($35.80 billion) replacement for the Collins Class submarine fleet, Davies said.

"The good news for her is that the core business of the defense department, which is running military operations, seems to be going pretty well," he said.

"But it's the long lead time stuff. The getting approvals of major projects through and then managing them, I think that's where the major bureaucratic heartache is going to be."

The Royal Australian Air Force is taking part in the US-led coalition campaign against Islamic State targets in Iraq and Syria. Australian troops are also helping to train Iraqi ground forces.

In August Abbott announced that two naval shipbuilding program, the A$20 billion SEA5000 Future Frigate project and the SEA1180 Offshore Patrol Vessels, would be brought forward to guarantee the continuous domestic construction of surface warships.

But the jewel in Australia's defence crown is the SEA1000 Future Submarine project, one of the world's most lucrative defence contracts and a thorny political topic.

Abbott and Japanese Prime Minister Shinzo Abe enjoyed a close relationship that saw Japan emerge as the early front runner for the programme, and his removal is seen as a setback for their bid.

Japan's reluctance to commit to building the submarines entirely in Australia, where manufacturing jobs are a hot political topic, has seen it lose ground to German and French proposals.

Payne joins a small number of woman defence ministers around the world and becomes the first to fill the role in an English speaking nation. Germany, Norway and the Netherlands all have female defence ministers.

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