A supporter of the activist group Anonymous holds a flare during a protest in London, Britain November 5, 2015. REUTERS/Stefan Wermuth

Anonymous has declared war against Turkey over Ankara’s support for Islamic State group militants.

The “hacktivist” group takes responsibility for a recent cyber-attack on Turkey as it claims to continue its war against the country as the hacker group believes the Turkey government backs ISIS.

Around 400,000 websites in Turkey went offline between Dec. 14 and Dec. 21 due to a Distributed Denial of Service. The websites apparently crashed due to excessive traffic. Turkish authorities could only counter the biggest cyber-attack in the country’s history when they blocked foreign web traffic.

A YouTube video, apparently published by Anonymous, claims Turkey supports ISIS by buying oil from the terrorist organization and by accommodating its fighters. “The news media has already stated that Turkey's internet has been the victim of massive DDoS attacks," an automated voice says in the video as a person with an “anonymous” mask reads.

"Dear Government of Turkey, if you don't stop supporting Isis, we will continue attacking your internet, your root DNS, your banks and take your government sites down."

The “anonymous” voice asks Turkey to stop the “insanity” as it leaves Ankara responsible for its fate. “"After the root DNS, we will start to hit your airports, military assets and private state connections,” the voice says. “We will destroy your critical banking infrastructure."

The leaderless hacking group does not have an official presence on the internet. Any person is allowed to start a Twitter account or make a YouTube video to declare cyber-attacks in the name of the hacktivist group.

According to The Independent, there have been speculations that Anonymous is acting on behalf of the Russian government. Russia has turned hostile against Ankara after Turkish authorities shot a Russian warplane down over the Syrian border in November.

Russia news agency RT reminds that Russia presented evidence in early December to prove Turkey’s involvement in oil trade with the terrorist organization.

Video: YouTube/Kurdistan