North Korea suffered a major Internet outage Monday in what was described as its worst network failure in years by the New York Times.

“I don’t know that someone is launching a cyber-attack against North Korea, but this isn’t normal for them. Usually they are up solid,” Doug Madory, the director of Internet analysis at Dyn Research, told Bloomberg. “This is not like anything I’ve seen before.”

Connectivity was restored after 9 hours and 31 minutes, according to Dyn Research. The outage follows several days of reported connectivity issues.

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The FBI has blamed North Korea for the major hack on Sony Pictures Entertainment, and President Obama has vowed a “proportional response.”

“They caused a lot of damage, and we will respond,” Obama said Friday. “We will respond proportionally, and we’ll respond in a place and time and manner that we choose. It’s not something that I will announce here today at a press conference.”

The White House declined to comment Monday. State Department spokeswoman Marie Harf told reporters that of the federal government responses, “some will be seen, some may not be seen.”

The Associates Press contributed to this report.