The United States has temporarily lifted its ban on military exercises with New Zealand for a third time in 14 months to take part in an exercise that began in the Persian Gulf last night.
The ban was imposed in response to the 1987 anti-nuclear legislation banning nuclear propelled or armed ships in New Zealand waters.
The exercise, "Exercise Leading Edge", involves 16 other countries and is under the auspices of the Proliferation Security Initiative, begun by United States President George Bush in 2003.
It is aimed at intercepting weapons of mass destruction or material used to make them.
The United States lifted its ban for other exercises under the PSI, in Singapore in August last year, and in Australia this year in March.
The waiver last year was the first for a joint exercise outside of an operation, such as allowing joint training with the New Zealand SAS before fighting together in Afghanistan.
For the three-day Leading Edge exercise, however, New Zealand's participants will remain based in New Zealand but take part as part of the command post.
United States Ambassador William McCormick said last night that the US participation did not represent a change of policy towards New Zealand's anti-nuclear legislation.
"It's true that certain constraints on the relationship still exist for both sides, but we are focused on exploring areas of co-operation that will benefit both countries and the wider region.
"The United States Government maintains flexible policies that allow us to meet the demands of our national security interests."
The United States Assistant Secretary of State, Christopher Hill, who has special responsibilities for North Korea, indicated in Fiji last week that New Zealand's anti-nuclear stance could, ironically, be of benefit in working with the United States on areas of non-proliferation.
Defence Minister Phil Goff said participating nations would work in groups. New Zealand's inter-agency team would be led by Defence Force personnel and would work in a syndicate with teams from Singapore, Japan, and Canada.
Other participants included Australia, the United Kingdom, Norway and the Netherlands.
Mr Goff said the United States was sponsoring the exercise.
"This is another example of both countries co-operating in areas of mutual concern while taking into account existing policy constraints."