Robert Ayson is Director of the Centre for Strategic Studies at Victoria University, Wellington.

US Defense Secretary Leon Panetta's arrival in New Zealand this morning is the surest sign of how far things have come, and how far they might go, in the strategic relationship between the two countries. 

Panetta has just been in North Asia, trying to calm down the crisis between ally Japan and peer competitor China. A trip to Auckland would therefore appear to be a doddle. But it's a long way from North Asia to New Zealand, and Panetta's trip has a purpose which goes beyond the symbolism of his visit being the first by a US defense secretary since Caspar Weinberger in 1982.

It's also about deepening practical military cooperation. A few months ago Panetta and his New Zealand counterpart Jonathan Coleman signed the Washington Declaration. This is all about a closer maritime defence partnership, and not just in the South Pacific. One media report has just quoted a US official saying that the aim was to 'engage in a dialogue with Wellington on where they see themselves in the rebalance, (and) where we can work together as part and parcel of this overall strategy.'

Yet this leaves New Zealand with a different kind of balancing act to play. There has been bipartisan support for closer relations with the US; after all, ties were improving when Helen Clark was still prime minister and George W Bush was president. But under John Key's right-of-centre coalition government and an Obama Administration pivoting towards Asia out of concern over China's influence, things have really accelerated.

And it's the China factor, another important relationship for New Zealand, that calls for some cool clear thinking about how far Wellington will go in the US relationship from here. Above all, don’t expect anyone except media commentators and rogue academics to raise the 'ANZUS' word. New Zealand and the US may be de facto allies now. And some trilateral cooperation involving Australia would not surprise. But it's probably convenient for New Zealand to have its long-standing nuclear-free position as a widely recognised obstacle to the resumption of formal alliance relations.

Photo of Secretary Panetta's arrival in Auckland this morning courtesy of Flickr user US Embassy New Zealand.