"The proposed sale will improve New Zealand's capability to meet current and future warfare threats by providing greater security for its critical infrastructure," the US State Department said in a statement.

"New Zealand will use the enhanced capability to strengthen its homeland defense," it added.

The State Department said in a separate statement that it had approved a $69 million sale of MK 54 torpedoes to New Zealand.

The State Department has notified Congress about the proposed sales, which still need to be approved by lawmakers.