In the event of an invasion or blockade the nuclear-free policy would be relaxed as needed. It is incredibly difficult to imagine a scenario where, say, China

In the event of an invasion or blockade the nuclear-free policy would be relaxed as needed. It is incredibly difficult to imagine a scenario where, say, China launches a naval invasion or blockade of NZ but is not already at war with our allies. In the latter case subs would engage their navy long before they reach NZ waters.