New Delhi, July 11 -- AUCKLAND - When Shane Jones, a minister in New Zealand's coalition government, called the prospect of Indian migration a "butter chicken tsunami," he was not speaking only about food. He was naming the scale of what was arriving, with more honesty than he intended. On Friday, Prime Minister Narendra Modi arrived in Auckland and signed what both governments are now calling a Strategic Partnership, the first elevation of this kind in India-New Zealand history. It was also the first visit to New Zealand by an Indian prime minister in 40 years. Jones's party lost that argument publicly and visibly.

The partnership was formalised during a state visit that lasted just over a day, a compressed itinerary that belied the den...