American Defence Secretary Leon Panetta has signalled the US would still like to see New Zealand alter its nuclear-free policy, despite the agreement to put the issue to one side, saying changing it would strengthen the relationship between the two countries.
Mr Panetta's comments follow an agreement to work around that roadblock, and a renewed commitment to co-operate more in the region, which has led the US to soften its policy on New Zealand ships.
Mr Panetta has left New Zealand after the first visit by a US Defence Secretary since 1982 - before New Zealand's anti-nuclear policy led to a breakdown in defence relations.
Mr Panetta announced the US would allow New Zealand navy vessels into American military ports for the first time since the policy was put in place, and remove restrictions on defence talks and exercises.
Despite describing that on TV One's Q+A programme as "a new era" in New Zealand-US defence relations, Mr Panetta made it clear the US was still hopeful New Zealand would change its nuclear-free stance.
He said that would be required if New Zealand was to return to an Anzus-style relationship of formal alliance with the US.
Asked if that was a goal for the US, Mr Panetta said it was a step-by-step process, "but ultimately if New Zealand is prepared to make revisions for the future, that would help strengthen our relationship. We will work together to help achieve that goal".
Under the "one fleet" policy, the US does not declare whether its vessels have nuclear capabilities - and New Zealand's non-nuclear policy means it will not allow a visit by any military vessel without confirmation it has no nuclear arms or power system.
Mr Panetta said: "I get a sense we're both headed in the same direction, and that's a good thing."
Defence Minister Jonathan Coleman made it clear during Mr Panetta's visit that that the anti-nuclear policy would not change.
Mr Panetta also said the US was "more than ready" to set up a base for the Marines in New Zealand, as it had in Australia and the Philippines. However, it was up to New Zealand to decide if it wanted that.
Prime Minister John Key has asked for a visit by a US Coastguard vessel, but Mr Panetta first brushed off the question, saying it was a matter for the President and Secretary of State. When asked again, he said the relationship was progressing one step at a time.
Asked whether the US had any expectations from New Zealand to reciprocate for removing restrictions on New Zealand vessels, Mr Panetta indicated it was a reward for New Zealand's deployment to Afghanistan.
New Zealand had deployed troops to that troubled country, and had fought alongside the United States in wars since World War I.
"Every relationship that is close is one that is based on trust," he said.
The US began to take a softer line on the anti-nuclear law in 2007, when the Prime Minister at the time, Helen Clark, met President George Bush in Washington and was given the message that Washington had begun to accept the policy and would look for ways to work around it.
The thaw has reached new heights under National and Barack Obama's Administration, including a formal agreement in the Washington Declaration to co-operate on defence.