The Green Party has confirmed it would send a Navy vessel to monitor Japanese whaling vessels when the season resumes in 2018.
Green Party leader James Shaw says it's New Zealand's moral obligation to "stand up to Japan" and "not stand idly by while vessels from that country slaughter these magnificent creatures."
On Tuesday, anti-whaling group Sea Shepherd said it would not confront Japan at sea when the whaling season resumed because of a lack of resources and an indication from Japan that they will have military back-up.
Captain Paul Watson singled out the New Zealand and Australian government for a lack of support, saying they are "hostile" and "in league with Japan".
"Sea Shepherd... is limited in resources and we have hostile governments against us in Australia, New Zealand and the United States," Mr Watson said.
Under a Green Government, Japan's activity would be monitored to ensure "unlimited whaling does not occur under the guise of scientific research", Mr Shaw said. He said Japan is testing New Zealand's leadership on activity in the Southern Ocean.
"Expressing disappointment is not enough. We need to show Japan that there are consequences to their decision to flout the International Court of Justice's ruling that scientific whaling is illegal."
On Tuesday, the Green Party announced it would establish a 30,000 square kilometre marine mammal sanctuary off the South Taranaki coast.