Have you read Yandex's SEC filing? If not, I encourage you to read the "Risks related to doing business and investing in Russia and the other countries in which we operate" section. http://www.scribd.com/doc/54292357/Yandex-F-1-Filing-With-SE... page 22.

(Easier link: http://constructive-project.org/en/articles/25.htm)