The Prime Minister says a multi-billion dollar boost for the Defence Force is about our national interest. 

The Government's unveiled its Defence Capability Plan, including $12 billion dollars of funding over four years - with $9 billion of new spending. 

Newstalk ZB senior political correspondent Barry Soper says the plan's 'surprising'.

"Remember, we said last week when it comes out that it'll be a 15-year plan. Well, this is more short-term - they're going to be spending, over the next four years, $12 billion dollars."

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