Johnston fights for more funds for defence

Defence Minister David Johnston needed to convince colleagues defence would be unable to mount short-notice missions such as its search for the missing Malaysian airliner if it did not get more cash.

In hard negotiations before the government's expenditure review committee, Senator Johnston made the point that defence would face serious problems if it had to endure more cuts.

As it turned out, defence was a big winner from the tough budget, with an increase of more than six per cent, taking funding to $29.3 billion in 2014/15.

Senator Johnston said finance and treasury officials acknowledged that defence had done it hard in the past five years, losing $16 billion.

"If we had to endure more cuts or absorb measures, there would be serious capability issues and we would be courting substantial difficulties," he told AAP.

Missions such as the ongoing search for Malaysia Airlines flight MH370, which at its peak featured four Orion maritime patrol aircraft and five ships, could only be launched at short notice because these units were maintained at a high level of readiness, he said.

The same applied to aid missions following the Japanese earthquake and the Philippines typhoon.

Most recently, at Christmas, two RAAF transport aircraft were despatched to help the UN peacekeeping mission in South Sudan.

Senator Johnston said it was expensive to maintain the level of readiness needed to be able to launch such missions at short notice.

"Those are the sorts of things we would not be able to do (without sufficient funding) and we would have to tell the national security committee and the prime minister we can't do this because we haven't got the money," he said.