These many reasons include his words, actions, policies, advisors, finances and friends.
Sometimes, if it walks like a duck, talks like a duck, looks like a duck, hangs around with ducks, waddles like a duck, lives in a pond, gets fed bread, and has been classified as a duck by experts the world over - it might just be a duck.
This is quite reassuring - if medvedev said it you know there’s no chance it could possibly happen.