North Korea disappeared from the internet at least twice in the past month, with state-run websites becoming inaccessible in what some observers speculated was a distributed denial-of-service attack on the country’s servers. In a report published Tuesday, a lone hacker bent on revenge told  wired that he was responsible for crippling the secretive country’s internet.

The American hacker — who goes by the handle P4x — told Wired he was one of the victims of a cyberattack last year on Western security researchers carried out by North Korean spies. He said he was frustrated that he was a target and that the US appeared to have a lacking response.

He said the hackers tried to snatch hacking tools and information on software vulnerabilities but he was able to stop them before they could get anything worthwhile. Nonetheless, there was a feeling of resentment, he told Wired.

“It felt like the right thing to do here,” P4x told Wired, adding: “If they don’t see we have teeth, it’s just going to keep coming.

“I want them to understand that if you come at us, it means some of your infrastructure is going down for a while.”

North Korea’s mysterious internet outages appeared around the same time the country was conducting record-breaking illegal weapons testing as it fired missile after missile. The timing of these developments led some expert observers to suspect that a state actor, such as the US, might be targeting North Korea, but P4x said that was not the case.

Wired reported that P4x provided screen recordings demonstrating his responsibility for the attacks on North Korea’s web servers. Insider has not reviewed these.

While the hacker was open about claiming responsibility for the attacks, P4x declined to disclose the vulnerabilities in the North Korean system he said he found and exploited to single-handedly take down the entire country’s internet on multiple occasions. He did say the attack was largely automated.

He told Wired it was “pretty interesting how easy it was to actually have some effect in there.”

P4x also told Wired he was trying to recruit more “hacktivists” to join a dark website he launched earlier this week called the FUNK project — which stands for FU North Korea.

“You can make a difference as one person,” the FUNK website reads, according to the report from Wired. “The goal is to perform proportional attacks and information-gathering in order to keep NK from hacking the western world completely unchecked.”