Some internet services have been restored in North Korea after an almost unprecedented internet outage, amid a cyber security row with the US.
Though there has been no comment from the authorities in Pyongyang, US experts reported the restoration.
Some analysts say the country's web access was cut entirely for a time.
Washington said it would launch a proportional response to a cyber-attack on Sony Pictures, which made a comedy about North Korean leader Kim Jong-un.
Officials would not comment on any US involvement in the current outages.
Services were partially restored after nine hours and 31 minutes of disruption, cyber security firm Dyn Research says.
The website for the state-run Korean Central News Agency (KCNA) was back online on Tuesday.
But the recovery looked to be partial and potentially unstable with other websites still inaccessible.
Analysts had said technical problems or a cyber-attack could be to blame.
Doug Madory of Dyn Research said they had seen a progressive degradation of North Korea's connectivity to the outside world until the point at which they were totally offline.
Arbor Networks, an internet technology service, said it had detected denial-of-service attacks against North Korea's infrastructure beginning on Saturday.
Only a small proportion of people have access to the internet in North Korea, one of the world's most secretive countries.
Last week, the US government said an FBI investigation had shown that North Korea was behind a hacking attack on Sony, which led to unreleased films and private emails being leaked online. North Korea denied being responsible.
But North Korea also praised the attack on Sony, and had for months condemned a Sony comedy, The Interview, which depicts the assassination of the North Korean leader. Sony eventually cancelled the cinema release of the film.
Mr Obama had said that the US would respond to the attack on Sony "in a place and time and manner that we choose".
On Monday, state department spokeswoman Marie Harf said the US would not discuss publicly "operational details about the possible response options, or comment on those kind of reports in any way, except to say that as we implement our responses, some will be seen, some may not be seen''.
The internet disruption came as the UN Security Council discussed North Korea's human rights for the first time, despite opposition from China and Russia.
US ambassador to the UN Samantha Power dismissed North Korea's demand to launch a joint investigation with the US into the attack on Sony, and threats to retaliate if the US refused.
"It is exactly the kind of behaviour we have come to expect from a regime that threatened to take 'merciless countermeasures' against the US over a Hollywood comedy, and has no qualms about holding tens of thousands of people in harrowing gulags," she said.
North Korean diplomat Kim Song said a decision on how to respond to the Security Council's move would be made in Pyongyang. "We totally reject the decision to bring DPRK [North Korea's] human rights record to the UN Security Council," he told Reuters.
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