At approximately 11am local time yesterday, Internet users around China reported significant Internet blackouts. Not only were they unable to access some Chinese sites, but also many foreign Web sites that had not previously been blocked.
The issue was not isolated to China. Web users in Hong Kong and Japan also reported issues with accessing Chinese sites. A number of explanations immediately came to light, with the most viable cause being the 8.7 magnitude earthquake in Indonesia on Wednesday, that might have damaged undersea cables.
However, reports from China's major telecommunication companies -- China Telecom and Unicom -- suggest that this was not the case. China Telecom confirmed that the earthquake had not interfered with the underwater cables in any way.
Both companies also shot down theories that the outage could have been caused by some sort of blip in the system, with Telecom insisting that there was no issue with their network. As all Chinese Internet traffic passes through the two networks' infrastructure to get overseas, this had seemed like a likely culprit.
With the mystery of what happened becoming murkier, many have been speculating as to what could have caused the blackout.
It was arguably far too quick to be a response to Anonymous' war rally against China's Great Firewall, which even they admitted will take time to crack.
Others have suggested that the temporary outage might have been a test run of an emergency 'kill switch', in case extreme measures need to be taken in the ongoing crackdown of the Chinese Internet.
According to Tech in Asia, VPNs that had previously allowed Internet users to get around the Great Firewall were down, but that smaller VPN providers seemed to be unscathed. This could suggest a deliberate targeting of such services, but at the moment, we can only speculate.
Admittedly, it does seem as though such a 'kill switch' would be extreme and far-fetched. However, the absence of clearer explanations lends the theory some credibility. China's Ministy of Industry and Information Technology has been silent over the blackout, and so have much of the state-run media.
China Daily, People's Daily and Xinhua, some of China's major news publications are continuing to cover the growing 'rumours' issue, but not the blackout.
It could be relatively insignificant, but as Wall Street Journal's Josh Chin points out, "the episode did illustrate just how jumpy China watchers and China Internet users have become in recent days."