What do you mean by this? Do you mean they hold Russian passports? Do they hold Ukrainian passports too? Do they live in Russia, or do they live in Ukraine? Have they previously lived in Russia or Ukraine? How does this mean that the Russian Government is responsible?
"Led by Russian officers"
Can you provide evidence of currently serving Russian officers 'leading' the opposition?
"Russian weapons"
If you are referring to Russian made weapons, these are extremely common throughout eastern europe. For example, here is a picture of a Ukrainian T-72, the AK-74 has been used by at least 23 governments throughout the world, and here is a picture of a Dragunov rifle used by the Armed Forces of Kazakhstan dated at 2003.
