TOKYO — The decision to ban Japan’s annual whaling drive off Antarctica, handed down by the United Nations’ highest court on Monday, was a hard-won victory for conservationists who long argued that Tokyo’s whaling research was a cover for commercial whaling.

The ruling by the International Court of Justice in The Hague halts a Japanese program that has captured more than 10,000 minke and other whales in the Southern Ocean since 1988 in the name of biological research.

Japan may not be ready to lay down its harpoons entirely. Though the ruling is final, it allows the Japanese to continue to hunt whales under a redesigned program, said Nanami Kurasawa, who heads a marine conservation group in Tokyo.

And the court’s decision does not affect smaller hunts that Japan carries out in the northern Pacific, or coastal whaling carried out on a smaller scale by local fishermen.