After talking to the Chinese diplomats, go towards the center aisle, between the sentry guns. Use the sniper view to see a man coming from the hallway and take him out. Then, immediately look to the left to see a soldier awaiting a Frag Grenade explosion. Shoot him in the head. Note: It is essential that you take out this soldier to succeed in the mission. Then, go to the room where the American soldiers are crouching. Stand in the doorway. Face the way the soldiers appear from. A soldier crouching will be going directly for that room. Take him out, and then move back to the center. As a colonel (the man with the red hat) throws a grenade, snipe him in the head. Then, move back into the doorway where the Americans are located. You will hear Grinko saying that he is coming and that he is ordering a man to come with him. Stand in the doorway and shoot the soldier that comes that way. Pick up the medkit and go back in the middle in between the sentry guns. Then, move forward towards the short concrete wall. Kill Grinko with either a snipe to the head of a Frag Grenade. As soon as you kill him, the mission will be completed.