The United States Navy is sending the USS Sampson to New Zealand, the first US warship to visit New Zealand in 33 years.
Prime Minister John Key said he had granted approval for the ship to visit to take part in the International Naval Review for the New Zealand Navy's 75th birthday celebrations next month.
Under New Zealand's anti-nuclear law, the Prime Minister has to be satisfied that any visiting ship is not nuclear armed or powered.
"I have granted this approval after careful consideration of the advice provided by the Ministry of Foreign Affairs and Trade," he said.
The law has never required foreign countries to confirm or deny whether their vessels are nuclear armed or powered.