The US and New Zealand defence ministries have announced the resumption of bilateral military cooperation after nearly three decades.

The improvement in military relations comes as part of the US strategy to pay more attention to the Asia-Pacific region, amid China's growing clout.

In 1986, Washington ordered a military embargo after New Zealand banned all nuclear-armed or nuclear-powered submarines from entering its waters a year earlier.

The US repealed its ban on New Zealand ships last year, and now its defence chief Chuck Hagel says Washington looks forward to deepening relations with Wellington.

"Having fought together in every major conflict of the last century, including Afghanistan, our bonds are rooted not only in our common interests as Pacific nations but also in the history and the values we share," he said.

New Zealand's defence minister Jonathan Coleman has welcomed the change in relations.

"We are looking forward to future cooperation with the US," he said.

"We're looking for common ground where we can extend cooperation."

The US defence secretary will also now allow a New Zealand ship to dock at Pearl Harbour for RIMPAC 2014, the world's largest international maritime defence exercise.

"This will be the first time a New Zealand ship will have visited Pearl Harbour in more than 30 years," Mr Hagel said.

Mr Coleman has also used the press conference to dismiss concerns about alleged National Security Agency surveillance of world leaders.

"We don't believe it would be occurring, and look, quite frankly, there would be nothing that anyone could hear in our private conversations that we wouldn't be prepared to share publicly," he said.

"A cartoon in our local paper...showed an analyst potentially listening to the communiqués from New Zealand, and a big stream of 'Z's' coming out, so I don't think New Zealand has got anything to worry about.

"We have high trust in our relationships with the US."

ABC/Wires