Someone really didn't want the world to know what Russian protesters thought about President Vladimir Putin's inauguration this week.

On Wednesday, hackers crashed a US-based site being used by activists to live-stream video of the anti-Putin demonstrations. According to Brad Hunstable, CEO of the online video company uStream, a massive “distributed denial of service” attack took the site down for nine hours. He said it was the third such attack from Russia in the past six months.

Cyber war ratchets up – on both sides

So far, it's been impossible to confirm that the cyber attacks came from the Kremlin – but it wouldn't be the first time. Russian activists have reported similar attacks on independent media outlets as protests against Putin's regime have gathered steam.

This time around, the hackers targeted the uStream channel used by Kirill Mikhailov. The 23-year-old Russian activist recently began streaming video live from the protests, to give people inside and outside Russia a view of what's actually happening on the ground.

But dissidents have not taken this lying down: in fact, they've pulled off some highly effective cybersabotage themselves. Earlier this year, the loose-knit hacktivist group Anonymous hacked into the email accounts of a pro-Putin youth group, to expose the Russian president's army of internet trolls. And just this week, the group claimed responsibility for crashing several Russian government websites, including Putin's own official site.

Further reading: Are Kremlin operatives using cyber attacks to squash democracy? A Russian journalist and a Russian security expert investigate.