The Prime Minister is on his way to the Cook Islands, to celebrate 50 years of their independence.

But the visit comes at a time when our typically close relationship is under stress.

Despite moving to self governance in 1965, the Cook Islands maintains a relationship of free association with New Zealand.

But the celebrations will likely have an undercurrent of tension.

The Pacific nation has just been forced to abandon a bid for greater autonomy, and even a seat at the United Nations, as it would have meant cutting some of those ties with New Zealand.