The customary response to challenges to defence spending is to evoke the shadowy threat of some "yellow peril" from the north. This relies on partial memories of the Imperial Japanese Navy's expansion into the Pacific in 1941, and simple racism. As readers will see in the attached chapters the People's Republic of China, and the Republic of Indonesia do not pose a military threat to New Zealand, or even Australia. There is simply no chance that either nation will invade either nation in a fifty year time period.
In fact the biggest threat to New Zealand is quite plain because it has recently devastated one of our biggest cities. New Zealand has suffered three deadly city shattering earthquakes in its short history. The 1855 Wairarapa-Wellington earthquake, the 1931 Napier earthquake, and the 2011 Christchurch earthquake. That is, one New Zealand city has been destroyed every eighty years. Only Chile and Japan have a worse record. Unlike Europe or Asia no New Zealand city has ever been destroyed as a result of war violence.
The 2011 Christchurch earthquakes have, to date, cost the country $40 billion. Seven years of World War Two cost New Zealand $49 billion (2015 dollars) (see War Expenses and RBNZ inflation calculator). Fortunately, because of generally excellent building standards, the magnitude 6.3 Christchurch earthquakes (with 2.2g peak accelerations) only claimed 185 lives, compared to World War Two which killed 11,700 New Zealanders through war violence. But it should not be forgotten that earthquakes are deadly. Haiti's 2010 earthquake killed over 100,000 from a magnitude 7 earthquake with 0.5g ground accelerations.
The other main threat to New Zealand is biological. This 2014 report[PDF] calculates a range of costs for a Foot and Mouth disease (FMD) outbreak at around $15 billion or about ten dollars in every $100 that changes hand each year. Foot and Mouth is one of the best known threats, but there are others. This report estimates the Psa-V bacteria is expected to cost the Kiwifruit industry around $800 million over fifteen years. Human diseases too have, in the past, proved deadly. The Spanish flu pandemic of 1918 claimed 8,600 deaths. This is the greatest loss of life due to a disaster in New Zealand's history.
While the defence force has had a role in earthquake and biosecurity threats, spending on defence does not greatly change either the hazard, or the potential damage from those threats. No number of rifles will kill the H5N1 virus nor stop a major earthquake or volcanic eruption in Auckland.
The Defence Assessment 2014 is a cleverly written document which tells the truth, but in a mildly deceptive way. Although it concludes that New Zealand faces no military threat in the foreseeable future it does emphasise the probable likelihood of armed conflict somewhere. The assumption is that this will become New Zealand's business through diplomacy. Essentially, however, it generally advances the view that New Zealand defence forces are a capability which makes itself useful in matters such as EEZ management, disaster response and search and rescue, none of which are military functions.
The sub-pages below show that with the exception of cyber sabotage there is no remotely credible threat to New Zealand which falls within the mandate of defence expenditure. We are instead largely defended by diplomacy, biosecurity agencies and the police. Incursions into our EEZ are carried out by unarmed civilian vessels.
The role of "defence" is not, therefore, defence. The role of New Zealand's $3 billion per year defence expenditure is something quite different.