Successfully complete one of the following tasks to get a trophy:

Assault Rifle - 3rd Class (Bronze): 250 assault rifle kills, 5 assault rifle kills with 15% accuracy in one game, 25 kills with 4 different assault rifles.
Pistol - 3rd Class (Bronze): 50 pistol kills, 2 pistol kills with 15% accuracy in one game, 5 kills with 3 different pistols.
SMG - 3rd Class (Bronze): 250 SMG kills, 5 SMG kills with 15% accuracy in one game, 25 kills with 4 different SMGs, 2 SMG headshots in one game.
Sniper Rifle - 3rd Class (Bronze): 100 sniper rifle kills, 3 sniper rifle kills with 30% accuracy in one game, 25 kills with 2 different sniper rifles.
Shotgun - 3rd Class (Bronze): 50 shotgun kills, 4 shotgun kills in one game, 15 kills with 2 different shotguns.
MG - 3rd Class (Bronze): 50 MG kills, 4 MG kills in one game, 15 kills with 2 different MGs.
Bronze Star (Bronze): 5 MVP awards, 25 kill assists, 300 kills, 35 headshots, 50 games on the winning side.
Stealth Medal (Bronze): 5 consecutive kills without taking damage, 25 kills with suppressed assault rifle, 15 kills with suppressed pistol, 20 kills with suppressed SMG, 20 kills with suppressed sniper rifle.
Admirable Service (Bronze): Escort 25 VIPs to safety, defuse 10 bombs, extract 25 hostages, defend 10 control points.
Distinguished Service Medal (Bronze): Capture 10 control points, plant 10 bombs, extract 10 hostages, escort 15 VIPs to safety.
Tour Of Duty Veteran (Bronze): Play 25 games of each game mode, play 25 games on each map.
Good Conduct (Bronze): Achieve 150 consecutive kills without killing a team-mate.
Special Operators Medal (Bronze): 75 sniper rifle kills, 15 kills in a row without dying, 25 melee kills, 3 headshots in a row.
Assault Rifle - 2nd Class (Silver): 600 assault rifle kills, 7 assault rifle kills with 20% accuracy in one game, 50 kills with 5 different assault rifles.
Pistol - 2nd Class (Silver): 100 pistol kills, 4 pistol kills with 20% accuracy in one game, 10 kills with 4 different pistols.
SMG - 2nd Class (Silver): 600 SMG kills, 7 SMG kills with 20% accuracy in one game, 50 kills with 5 different SMGs, 3 SMG headshots in one game.
Sniper Rifle - 2nd Class (Silver): 200 sniper rifle kills, 4 sniper rifle kills with 35% accuracy in one game, 50 kills with 3 different sniper rifles.
Shotgun - 2nd Class (Silver): 100 shotgun kills, 6 shotgun kills in one game, 25 kills with 3 different shotguns.
MG - 2nd Class (Silver): 100 MG kills, 6 MG kills in one game, 25 kills with 3 different MGs.
Silver Star (Silver): 20 MVP awards, 1,000 kills, 15 consecutive kills without taking damage, 100 headshots, 200 games on the winning side, bronze star, stealth medal.
Military Cross (Silver): Extract 50 hostages, eliminate 50 VIPs, defuse 25 bombs, plant 25 bombs, capture 35 control points, meritorious service medal, distinguished service medal.
POW Medal (Silver): Play 50 games of extraction without killing a hostage.
Marksman Medal (Silver): Achieve 15 kills in a game with accuracy above 75% (explosive kills do not count).
Expeditionary Medal (Silver): Play 50 games as a mercenary, play 50 games as a commando/special forces.
Assault Rifle - Elite (Silver): 1,000 assault rifle kills, 10 assault rifle kills with 25% accuracy in one game, 75 kills with 7 different assault rifles.
Pistol - Elite (Silver): 150 pistol kills, 35 pistol headshots, 6 pistol kills with 25% accuracy in one game, 20 kills with 5 different pistols.
SMG - Elite (Silver): 1,000 SMG kills, 125 SMG headshots, 10 SMG kills with 25% accuracy in one game, 75 kills with 5 different SMGs, 4 SMG headshots in one game.
Sniper Rifle - Elite (Silver): 350 sniper rifle kills, 75 sniper rifle headshots, 6 sniper rifle kills with 90% accuracy in one game, 60 kills with 3 different sniper rifles.
Shotgun - Elite (Silver): 250 shotgun kills, 60 shotgun headshots, 8 shotgun kills in one game, 60 kills with 3 different shotguns.
MG - Elite (Silver): 250 MG kills, 75 MG headshots, 8 MG kills in one game, 60 kills with 3 different MGs.
Purple Heart (Silver): 50 kill assists.
Superior Service Medal (Silver): 1 MVP award on each map, 1 MVP award in each game mode, 200 kills as a mercenary, 200 kills as commando/special forces.
Meritorious Service (Silver): Win 25 rounds via hostage rescue in extraction, win 25 rounds via bomb defusal in demolition, win 25 rounds via VIP extraction in escort.
Demolitions Expert (Silver): 10 grenade kills, 2 breaching charge kills, 2 claymore kills, 10 kills by blowing up cars or other explosives.
Gallantry Medal (Gold): 200 sniper rifle kills, 5 MVP awards on each map, 50 melee kills, special operators medal, superior service medal.
Legion Of Merit Medal (Gold): 50 MVP awards, 5,000 kills, 250 headshots, 500 games on winning side, extract 150 hostages, plant 100 bombs, capture 125 control points, eliminate 125 VIPs, silver star, military cross, gallantry medal, all service medals, all weapon specialties elite.
Confrontation Champion (Platinum): Get all gold, silver and bronze trophies.