Defence Minister Wayne Mapp says a review may lead to spending cuts as a result of sharing more resources between the New Zealand Army, Navy and Air Force.
A former chief executive of Telecom, Roderick Deane, will lead what is being called the Value For Money review.
Wayne Mapp, told Morning Report that, historically, there haven't been a lot shared services around things that could be done on a joint basis, such as training and human resources.
Dr Mapp says defence is spending about $2 billion bringing new capabilities on stream, pushing up depreciation and operational costs, and savings need to be made.
The minister says the next few years will be a challenging time for all government departments.
Listen to Morning Report interview with Wayne Mapp