Currently, Aviation SE has the tag russia, which is used for questions on the Russian Federation. However, questions on Russian aircraft often (mis)use this tag. Hence, I do believe it would be useful to have the tag russian.
For example, the Sukhoi Su-30 is a Russian aircraft, but it is operated not only by Russia, but also by Venezuela. Why use the tag russia when asking about aircraft designed and manufactured by Russia and then exported?
Suppose I want to search for questions on Russian fighters. Searching for
[russian] [fighter] is:question would be more efficient than searching all tags starting with "mig" or "sukhoi".