The leader of the environmental movement Sea Shepherd says the group will refocus its attention on stopping whaling by Norway and other European nations if Japan abides by a United Nations court order.
Paul Watson, founder of the US-based organisation, welcomed the decision by the International Court of Justice in The Hague, but he voiced doubts about Japan's pledge to comply with the ruling.
He said his group - which has systematically harassed Japan's whaling fleet - would send its three ships to the Atlantic if Japan ended its practice.
"I'm not 100 per cent convinced they will abide by the ruling. They tend to agree and then do whatever they want to do anyway. That has been the history with the International Whaling Commission," Watson said. "Our ships will be prepared and ready to return if they return," Watson said. "And if they don't return, then we'll be able to refocus our efforts against Norwegian, Icelandic and Faroese whaling."
Watson credited Sea Shepherd's efforts with saving more than 5,000 whales since 2002 in the Southern Ocean, where Japan carried out its expeditions even though the area was declared a whale sanctuary. Australia hauled Japan before the International Court of Justice in an effort to stop the hunt.
Japan, while insisting that whale meat is part of its culinary heritage, has argued it is technically abiding by a 1986 moratorium on commercial whaling by using a loophole that allows "lethal research" on the ocean giants.
Watch: Japan says will honour ICJ whaling decision
Norway and Iceland openly defy the ban on commercial whaling, but Watson said that Sea Shepherd has not had the funding to support "a two-front battle". Sea Shepherd has already carried out protests against whaling in the Faroe Islands, an autonomous province of Denmark, where residents traditionally kill pilot whales after driving them into small bays or fjords.
Japan has slapped Watson with an Interpol red alert seeking his arrest over damage to a vessel. He was arrested in 2012 in Germany on a warrant from Costa Rica, where he is wanted for an ocean confrontation over shark finning a decade earlier.
Watson, who was born in Canada and also holds US citizenship, fled Germany and said he has been living openly in the US state of Vermont with no effort to arrest him. He hoped that the court decision would weaken Japan's case and make it less likely for other countries to arrest him if he travels for Sea Shepherd activities.
"Japan hasn't made any effort to ask for my extradition from the United States," he said. "But what I think they want to do is just keep me on the list. They don't want to try me - they just want to stop me from moving."