Only two Pacific Island countries were present, Tonga and Papua New Guinea. Fiji which is still under military rule was excluded.
The other participants were New Zealand, Australia, France - which has Pacific territories - and Chile. While it is a Pacific Rim country, It is not clear why Chile has been included in a South Pacific ministerial grouping. The driving force for the new grouping has been Australian Defence Minister Stephen Smith.
The meeting comprised both ministers and several defence chiefs. It is not clear yet whether the meeting will become an annual event or just a regular event.
Initially the grouping is likely to concentrate on humanitarian and disaster relief and maritime surveillance.
The treaty was signed with Tongan Prime Minister and Defence Minister Lord Tu'ivanako.
New Zealand's engagement with Tonga comes after a period of concern about the transition to democracy in Tonga.
A leaked briefing paper in 2003 by the High Commissioner at the time Bryan Smythe said the Tongan Defence Service regarded the democracy movement as "the enemy'' and that
contact with the New Zealand army under a mutual assistance had not changed that.
Tonga has since had undergone its first democratic elections with the current Prime Minister being the first one not appointed by the King.
Tonga has a defence force of about 600 and with about 50 serving in Afghanistan, has one of the highest commitments per capita in Aghanistan.