Threats to NZ‎ > ‎


Map number of cargo ships at sea 10 March 2016

A blockade (sea) would require an enemy to station warships on the sea approaches to New Zealand. Given that New Zealand ships can sail West around Australia, north around PNG, or East to the US, Panama or Cape Horn imposing a sea blockade on New Zealand would be extremely difficult to any Navy. The main point of vulnerability is fuel imports. New Zealand has it's own refinery so oil can be shipped from any of these directions. It also produces its own oil.
The most effective weapon to blockade New Zealand would simply be diplomatic and commercial pressure. This could be used to simply deny New Zealand access to world oil and divert shipments destined for this country. New Zealand's fuel stocks would be exhausted in two months crippling our economy.
In World War Two New Zealand lost shipping to German raiders. The auxiliary cruisers Komet and Orion sank the RMS Niagara and the RS Rangitane along with another eleven smaller ships using sea mines. German raiders in World War One were less successful.
While it would be possible for a covertly hostile power to interfere with our merchant shipping this would soon become a source of international attention.
It is unlikely that New Zealand could be physically blockaded by any nations other than Australia or the United States and even these nations would find it easier to simply cut off our oil supply using diplomacy.