An F/A-18E Super Hornet participates in an air power demonstration over the aircraft carrier USS John C. Stennis.

The prime minister insists the government is not going to review New Zealand's nuclear-free stance, and doing so would be detrimental to our relations with other countries, according to a former defence minister.

Though the opposition is sceptical of the government's commitment to the four-decade-old stance.

Defence Minister Chris Penk, speaking at a security summit in Singapore last week, said it would be helpful to have a conversation about nuclear propulsion, to the extent that it is different to nuclear weapons.

There was no policy along those lines, Penk said, but it would be "helpful" for the country to have "a conversation", given Australia was slated to acquire three nuclear-powered submarines as part of the AUKUS deal.