A fleet of international warships is bypassing Auckland's historic naval celebrations and heading for Kaikoura to assist with the earthquake response.
The fleet includes the first United States warship to visit New Zealand in 33 years.
The USS Sampson was due to enter Auckland Harbour today for the International Naval Review as part of celebrations for the 75th anniversary of the Royal New Zealand Navy.
The historic visit is the first since the Anzus rift in the 1980s sparked by New Zealand's landmark anti-nuclear policy.
However Defence Minister Gerry Brownlee confirmed that New Zealand had accepted offers of help with the quake recovery from five nations attending the International Naval Review - the United States, Australia, Canada, Japan and Singapore.
"The USS Sampson, an Arleigh Burke-class destroyer, has departed from the Hauraki Gulf and is now on its way to Kaikoura, where it will deploy two MH60 helicopters to help as required. The US has also offered a P-3 Orion for surveillance flights," Brownlee said.
The Australian Defence Force has diverted the HMAS Darwin from her planned participation review.
"The Darwin is expected to arrive off the Kaikoura coast on Wednesday evening and will deploy its Seahawk helicopter from offshore. Canada is sending its frigate the HMCS Vancouver."
Brownlee said the New Zealand Navy had already sent HMNZS Canterbury and HMNZS Wellington to Kaikoura and would also send HMNZS Te Kaha and tanker ship, HMNZS Endeavour.
"It's heartening to see overseas partners so willing to alter their plans and offer their assistance.
"The International Naval Review is all about celebrating 75 years of the Royal New Zealand Navy and the bonds it has forged globally.
"Despite the changes to the planned celebrations, it's poignant to see the anniversary marked with such cooperation and camaraderie."
Brownlee said captains of the vessels would have been torn between attending the naval celebrations and "reaching out to offer their services".
"While the New Zealand Defence Force was well placed to respond to the unfolding situation in Kaikoura and surrounding districts, we are grateful for the help offered."
Hundreds of New Zealand defence force personnel are already helping with the recovery effort following Monday morning's magnitude 7.5 quake. The disaster triggered massive slips, cutting off towns and destroying homes.
Two people died in the earthquake and hundreds of others remain in emergency shelters.
Civil Defence director Sarah Stuart-Black, speaking from the bunker at the Beehive this morning, said the defence force evacuated about 200 people yesterday.
Between 700 and 1000 people still need help leaving the area.
About 75 per cent of Kaikoura was expected to have access to the water supply by mid morning today.
She said the extra help from the Sampson and other ships meant the number of helicopter trips in and out could ramp up.
Asked if that meant more than 200 people could be evacuated today, Stuart-Black said "I would like to think so", but that would depend on weather and other factors.
The New Zealand navy ships are due to deliver much needed supplies to the cut-off town and ferry out those still awaiting rescue.
A US embassy spokeswoman had few details about the USS Sampson's mission, but confirmed it would assist New Zealand defence personnel with the recovery, missing today's historic naval review.
The review had been scheduled to take place tomorrow but was brought forward by 24 hours because of expected bad weather.
The remaining fleet will enter Waitemata Harbour in four divisions between 6am and 2pm.
Prime Minister John Key said last month he had granted approval for the US ship to visit to take part in Navy's birthday celebrations.
Under New Zealand's anti-nuclear law, the Prime Minister has to be satisfied that any visiting ship is not nuclear armed or powered.
"I have granted this approval after careful consideration of the advice provided by the Ministry of Foreign Affairs and Trade," he said at the time.
The law has never required foreign countries to confirm or deny whether their vessels are nuclear armed or powered.
But the US chose not to send any ships as part of the reprisals for the anti-nuclear policy, which effectively suspended New Zealand from the Anzus security alliance in 1985.
"The process for considering the visit by the USS Sampson is the same as that used for all ships attending the International Naval Review. This process has been used for all military ships visiting New Zealand since the legislation was enacted.
"New Zealand looks forward to the USS Sampson's participation in the International Naval Review to mark the Royal New Zealand Navy's 75th anniversary. The visit is a further reflection of the depth of the bilateral relationship with the United States," Key said.
The USS Sampson is an Arleigh-Burke class destroyer and is 155m long.