Nissan decided to close down its global corporate sites as well as the site of its Japanese domestic market as a precautionary move against an attempted cyber-attack from a hacker believed to be connected to Anonymous.

The company's administrators said the attack is a denial-of-service (DDos) type, with the attacker flooding the site with numerous visits as a way to block other users.

When a site receives an overwhelming number of visits, its servers become heavily affected, causing the site's whole operation to go down.

They also linked the attack to someone who is connected to the group known as Anonymous, and it is said to be part of an on-going anti-whaling campaign. Hashtags such as #OpKillingBay and #OpWhales were reportedly being used for the campaign, and have been seen over Twitter.

While the attacker is said to be linked to Anonymous, the anti-whaling campaign is not officially sanctioned by the hacktivist group.

As a way to prevent customer or corporate data from potential leaks, Nissan had to bring down their sites in an offline state.

"Customer privacy and security is of utmost importance, and we take any potential threat to our information systems seriously," said David Reuter, Nissan spokesman, in a statement to Auto News.

Nissan's global media site and its U.S. site were not affected and seemed to be working normally.

The attack is just one of the various attacks against Japanese websites in what appeared like a continued display of anti-whaling sentiments. Not even the official site of Japan's prime minister was spared from the attack.

Whale hunting in Japan has been part of the country's long tradition. Today, whale hunting is being sustained by the country's fisheries agency, which validated the activity as an integral component in scientific research.

The country's whaling program started in 1987, a year after the enactment of an international moratorium. Critics of the program were perceived as overly sentimental and unconscious of the scientific evidence underlying the program's sustainability measures. Moreover, Japan believes that most whale species do not belong to the endangered category and that hunting whales for food consumption is simply a part of the country's food culture.

In late November, the Japanese government said that the country will resume whaling early in 2016 after taking a break for over 12 months. Its so-called "scientific" whaling program will only involve hunting minke whales, with the number being reduced to only one third of the ones that were caught in the previous program.

Nissan said that the hacker and its cyber-attack attempt in line with the anti-Japan whaling program is beyond the scope of their business.