Here is the full list of all 12 Special Forces: Team X achievements.
Reach Operator Rank 40
Kill 20 enemies in a match
Kill an enemy with his own mine
Reach Operator Rank 20
Achieve a teamplay multiplier of 4x or better
Complete one Player Mission
Reach Operator Rank 2
Kill four enemies with a single explosive
Complete all Player Missions
Win a match in all Game Types
Execute 25 enemies
Kill 25 enemies with an attack dog