Defence Minister Jonathan Coleman has signed a non-binding agreement with the United States Department of Defence formalising areas of co-operation.
Mr Coleman has just finished his first official talks with US Defence Secretary Leon Panetta in Washington.
The minister says the agreeement ties together co-operation already in place in the areas of maritime security, humanitarian security and disaster relief.
The visit coincides with New Zealand's return to the Pacific Rim naval exercise, Rimpac.
The world's largest international maritime warfare exercise takes place every two years and the next is scheduled from 29 June to 3 August around Hawaii.