Former Prime Minister Jim Bolger says difficulties in New Zealand's relationship with the United States over the nuclear-free stance are gone thanks to the presidency of Barack Obama.
Mr Bolger, who also chairs the US-New Zealand Leadership Forum, says New Zealand's anti-nuclear position was once considered a rock on the road.
However he says Mr Obama - who invited Prime Minister John Key to a nuclear security summit in Washington this week - changed that with his aim to rid the world of nuclear weapons.
PM wraps up visit to North America
Prime Minister John Key has finished his North American visit amid signs New Zealand's anti-nuclear policy is no longer an irritant in the relationship with the United States.
Mr Key was invited to a two-day nuclear security summit in Washington earlier in the week because of New Zealand's anti-nuclear policy.
Labour Party leader Phil Goff says there has been a significant shift in American thinking but it will not necessarily make negotiating an international trade deal involving the US any easier.
The Trans-Pacific Partnership involves eight countries, including the US.
Mr Goff says the American farm lobby will still fight the deal as strongly as ever.