The activist hacker group Anonymous claimed Wednesday evening to have infiltrated and taken control of North Korea’s official news and propaganda website, www.uriminzokkiri.com, as well as its Flickr account. On Thursday morning, the hacktivist collective followed up by assuming control of North Korea's Twitter account. The cyber-attack comes amidst growing tensions after North Korea threatened South Korea and the United States with nuclear attacks.

On April 3, Uriminzokkiri’s Flickr account, which usually features North Korean leader Kim Jong-un participating in official activities, uploaded an image of tango dancers wearing Guy Fawkes masks with the words “Tango Down.” This morning, that image replaced Uriminzokkiri‘s Twitter avatar, and the account sent a tweet that simply reads “Hacked” with links to official North Korean Web properties. All of these websites remain closed at the time of writing, including Uriminzokkiri’s home page.

The Flickr account continued to upload images that reference Anonymous, as well as an image of Kim Jong-un with pig-like ears and a snout, indicting the dictator for human rights violations.

Last week, Anonymous threatened North Korea with a post on HTMLpaste, demanding a stop to nuclear threats, Kim Jong-un’s resignation, direct democracy in North Korea and uncensored access for North Korean citizens.

“We are inside your local intranets / We are inside your mailservers / We are inside your webservers,” the Anonymouse statement reads. “First we gonna [sic.] your data, then we gonna wipe your bad*** dictatorship ‘government.’”

The statement also claimed to have more than 15,000 membership records from Uriminzokkiri, and even leaked a few of them.

On Wednesday, a follow-up was posted to Pastebin, calling the attack #opNorthKorea and explaining how it infiltrated North Korea’s country-wide intranet. The statement threatened to “inject the kittens and porn” into Korea’s network, and released thousands of additional Uriminzokkiri membership records.

Cyber warfare is increasingly a part of the conflict between North and South Korea. On March 20, three South Korean banks and a number of broadcast networks were shut down in a malware attack. Earlier in March, North Korea accused the U.S. and South Korea of attacking its Internet system.

To combat these cyber attacks, South Korea has established a new government department dedicated to cyber security. It has been training a “cyber unit” of nearly 3,000 people in case of an attack by North Korea, and has been running cyber warfare exercises with the U.S.