Looks like you don't understand what nationality is, if you're asking what is "Russian". To be Russian one needs to be Russian ethnically. If non-Russian lives in Russia, it doesn't make him Russian. If non-Russian speaks Russian language, it doesn't make him Russian either.

BTW, in our language different words are used for ethnicity - русский, for Russian citezenship - россиянин, and for person who consider Russian his native language - русскоязычный (все русские, за редким исключением, - русскоязычны, но не все русскоязычные - русские).