Stopping the queenside expansion of the white pieces.
1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1c4  3... f8c5  4. c2c3  4... g8f6  5. d2d3  5... e8g8  6. e1g1  6... d7d6  7. c1g5 A  favorite line of the Armenian GM. 7... h7h6  8. g5h4  8... g7g5 The principled choice. This is what makes the Bc1-g5  maneuver somewhat risky for White. He may end up with a permanently locked bishop. 9. h4g3 