SEAL Team Six was part of the U.S. military assault on the Middle East, and was involved in the attack on the country's capital city, where Opfor military leader Al-Asad was believed to be located. During the level "Shock and Awe", SEAL Team Six detected and confirmed a nuclear device at the center of the city, and notified U.S. field command, which dispatched NEST teams to neutralize the warhead. However, they were unsuccessful, and the nuclear warhead detonated with substantial casualties to U.S. military forces. Because the SEAL Team Six were the ones who discovered the device, it can be assumed that they were in the vicinity of the nuke when it detonated and that they were killed.
SEAL Team Six makes brief appearance in the campaign level, 'Demon Within'. After The Player interfaces Sarah Hall's DNI and enters her subconscious, several corpses of SEAL Team Six members can be seen lying on the fourth tree.
It would seem that the SEALs wear two different uniforms throughout the game: One that has a Multicam pattern, and another that is a more futuristic digital pattern. Another pattern is found on Uplink, where they wear a desert camouflage similar to the U.S. Marines in Call of Duty 4.
The SEAL Team Six assault rifle character model is the same as Crosby's, albeit with futuristic digital camouflage.
The SEAL Team Six SMG character model wears a similar uniform to Mike Harper's.
The SEAL Team Six LMG character model wears the same suit as Javier Salazar.
In early trailer and screenshots, the SEALs had a different model and colours on their gloves.