Dutch - Leningrad - Karlsbad variation
1. d4 f5 2. g3 g6 3. Bg2 Bg7 4. Nh3
White pushes the queen's pawn to d4. Black advances the f-pawn to f5. White advances the g-pawn to g3.
Black pushes the g-pawn to g6. White develops the light-squared bishop to g2. Black develops the dark-squared bishop to g7.
White develops the knight to h3.