The hacktivist collective Anonymous says it was responsible for the downing of the website of a Japanese airport over the weekend. The website of Narita International Airport near Tokyo went offline for several hours on 22 and 23 January, with the airport's operator confirming that the site was the victim of a Distributed Denial of Service (DDoS) attack.
DDoS attacks work by flooding a website or network with artificial traffic, eventually overwhelming it and knocking it out for hundreds of thousands of internet users.
Officials told the Japan Times newspaper that while passengers were unable to access flight information on the website over the weekend, flights operated normally.
Immigration authorities refused Ric O'Barry, 76, entry into Japan on a tourist visa after reportedly accusing him of planning to support a campaign against the slaughter of dolphins.
O'Barry was featured in the 2010 Academy Award-winning documentary, The Cove, which investigates the annual culling of dolphins in the southern Japanese town of Taiji.
Activists say 20,000 dolphins, small whales and porpoises are killed for their meat by Japanese whalers and fishermen every year.
The annual culling at Taiji, where wild dolphins are herded from the open ocean into a shallow pen and then killed using metal poles, has been the subject of international criticism for its cruelty.
But defenders of the practice say it provides income for local residents and point to the fact that the animals being targeted are not endangered.
Anonymous – a loose coalition of hackers and activists – has targeted Japanese websites in the past in protest against the country's whaling practices, and recently took down the global website of automobile manufacturer Nissan.