Russia. Because:
1. It's still the Soviet Union, just smaller and with a different name.
2. Someone needs to show the world just how pathetic and tiny a man Putin really is. He's simply trying to act the tough guy because he knows that he's actually a shadow of a fallen regime and trying desperately to maintain power in a world that knows he is truly insignificant.
I would send spies and agents to infiltrate the FSB and the Kremlin and slowly, over a period of time, turn as many as I can to an apparent 'revolutionary' group, secretly led by me. I would also be using whatever resources available to turn the Russian people to my side. Stay in the shadows until the uprising, at which point I send weapons and soldiers to help the people, capture (NOT kill) Vladimir Putin, and then put him on trial and execute him for crimes against the Russian people. Using my influence in the region I would finally make certain to install people in power who are much more likely to work for the people, and also make friends with the West properly and eliminate any traces of the Soviet era, while also making sure enough people are in power who are affiliated with me and my nation. Just in case...