Kasparov.ru is still up for me. Didn’t check the others.
http://www.washingtontimes.com/news/2014/mar/13/kremlin-blocks-opposition-websites-kasparov-fears-/
Former world chess champion and Kremlin critic Garry Kasparov, whose website was taken down within Russia, tweeted: “Obviously Putin is preparing something drastic if he’s blacking out the last sources of truth in Russia. I fear for the safety of Ukraine.”
He added that the sudden censorship could possibly be a ruse because “Putin plays many games [and] always raises the stakes when possible. [The] West is easily bluffed, he finds. […] Good luck getting other countries to give up their nukes or nuclear programs now, with UK/US security guarantees to Ukraine in the trash.”