Marise Payne
Minister for Defense Marise Payne is sworn in by Governor-General Sir Peter Cosgrove during the swearing-in ceremony of the new Turnbull Government at Government House on Sept. 21, 2015, in Canberra, Australia. Getty Images/Stefan Postles

SYDNEY (Reuters) - Australia on Monday swore in its first female defense minister, Senator Marise Payne, who will oversee open-ended military engagements in two countries and some of the country's most important defense 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 formerLiberal Party prime minister John Howard.

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

Defense 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 theAustralian Strategic Policy Institute.

Abbott centralized decision making in his office and locked his defense 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 U.S.-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 defense crown is the SEA1000 Future Submarine project, one of the world's most lucrative defense 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 program, 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 defense 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 defense ministers.