I am a magnificent bastard. It is currently Fall.
I'm playing Germany, you see, and last Fall Russia took Rumania. He lost it to Turkey (with whom I am allied) this Spring.
This means that he has five troops and four supply centers to support them. I am almost certain I can predict his moves. He will try to take Romania from the Black Sea with support from Galicia and Sevestopol. Turkey is attacking Sevestopol from Armenia, and I shall attack Galicia from Bohemia. Meanwhile, Serbia is being attacked from Bulgaria and Greece. Norway is going to move into Petersburg.
Now, look at this from his perspective. I also have to save my skin because I have five units and four supply centers. Obviously, I'm going to take Denmark- I can't take anywhere else. What he will assume is that I will take Denmark from the Baltic with Swedish support, since I would be a fool to abandon Sweden when I have an alternative. He is likely to move into either the Baltic (unlikely) or back to Petersburg to protect it (more likely). Without any support to keep it from bouncing, there is simply no reason to move into Sweden. It accomplishes nothing and leaves Petersburg open to attack. In addition, since he should be deathly afraid of losing another supply center, Warsaw will hold.
As a result, I am making a move that should- if it ever crosses his mind- appear so preposterous, bullheaded, pointless and dangerous that he will simply reject it out of hand. The smart move for him, then, is to go back to protect Petersburg. As shown above, knowing that Warsaw will hold, A Prussia will move to Warsaw. A Munich will move to Silesia (France is not going to attack it, he will assume it'll just bounce), and F Baltic will move to Prussia. Next turn, I can take Warsaw for sure, and beyond that- probably-Moscow.