Greenland police said they apprehended veteran environmental activist and anti-whaling campaigner Paul Watson on an international arrest warrant issued by Japan.

Watson, a 73-year-old dual Canadian and American citizen, is a former head of the Sea Shepherd Conservation Society whose direct action tactics include high-seas confrontations with whaling vessels. They have drawn support from A-list celebrities and featured in the reality television series Whale Wars.

He was arrested Sunday when his ship docked in Nuuk, Greenland's capital, a police statement said. 

On Monday, the Captain Paul Watson Foundation said he would be detained in Nuuk at least until Aug. 15, to give the Danish justice ministry — Greenland is an autonomous territory of Denmark — time to investigate the case and possible extradition. He faces a maximum sentence of 15 years in prison in Japan, according to the foundation.

His foundation also said the Greenland court wouldn't allow Watson's release on bail as he was considered a flight risk.

Prominent U.S.-Canadian anti-whaling activist arrested in Greenland

Paul Watson, a well-known U.S.-Canadian anti-whaling activist, was arrested on Sunday. The founder of the Captain Paul Watson Foundation was detained in Greenland and faces extradition to Japan where he is wanted for allegedly blocking Japanese whaling.

Watson on mission to stop Japanese whaling ship

The foundation described more than a dozen police officers boarding the vessel and leading Watson away in handcuffs when it stopped to refuel. The foundation said the ship, along with 25 volunteer crew members, was en route to the North Pacific.

According to his foundation, the ship was due to sail through the Northwest Passage to the North Pacific to confront a newly built Japanese factory whaling ship, "a murderous enemy devoid of compassion and empathy hell-bent on destroying the most intelligent self-aware sentient beings in the sea."

"The arrest is believed to be related to a former Red Notice issued for Captain Watson's previous anti-whaling interventions in the Antarctic region," the foundation said in an emailed statement on Sunday.

Neither the Japan Coast Guard nor Japan's foreign ministry, which had issued the international warrant for Watson, confirmed they are negotiating Watson's handover. However, the coast guard, the primary investigative authority in Watson's case in Japan, said Monday that officials were on standby if a handover is ordered.

Japan does not have an extradition treaty with Denmark and it is unknown if or when Watson would be handed over.

"We implore the Danish government to release Captain Watson and not entertain this politically motivated request," Locky MacLean, the foundation director, said in the statement.

Watson has been arrested before

It's not the first time Watson's tactics brought him head-to-head with authorities. He was detained in Germany in 2012 on a Costa Rican extradition warrant but skipped bail after learning that he was also sought for extradition by Japan, which has accused him of endangering whalers' lives during operations in the Antarctic Ocean. He has since lived in countries including France and the United States.

Watson, who left Sea Shepherd in 2022 to set up his own organization, was also a leading member of Greenpeace, but left in 1977 amid disagreements over his aggressive tactics.