AUCKLAND, New Zealand — Defense Secretary Leon E. Panetta arrived in this South Pacific island nation Friday, becoming the first Pentagon chief to visit in three decades, an absence prompted by a breakdown in ties after New Zealand prohibited US nuclear warships from its territorial waters.

In a sign of Washington’s efforts to increase military-to-military cooperation, Panetta announced that the Obama administration had modified US policy so that in the future, the defense chief can authorize individual visits by New Zealand naval ships to Defense Department or Coast Guard facilities.

Although New Zealand now participates in US-led naval exercises, its ships must dock at commercial ports in the United States, and not at military bases — a reciprocal ban in response to that imposed by New Zealand on US warships.

“The deep respect the United States military has for the New Zealand defense forces has only grown over this decade of war,’’ Panetta said at an Auckland news conference.

The closer relations have resulted in the United States and New Zealand signing new documents to reestablish avenues for dialogue and pledging cooperation on Asia-Pacific security issues.

Panetta said he did not seek a renewed treaty.