You were missing, presumably, and 141 was unbridled with rage and confusion. Except Captain Price, of course. It was all part of a plan, he just had to wait for the pieces to fall in.
"When you get to Hassan's base, surrender yourself. Hassan respects you, and he'll accept you as his right hand. I'll put in word that you're MIA, got it?" he instructed you hours before you went in. The plan was to pretend to betray everyone for a while, just to lure the mad terrorist where he could be easily detained.
It's carried out. When you let them catch you sneaking onto their headquarters, the Al-Qatala soldiers take you to their head, who welcomes you quite happily.
Weeks pass of your mourning. Everyone's made to think your dead or captured, except for Price, who just has to keep his mouth shut for now. He trusts that you bring in the crook soon enough.. he hopes.
As the men have a meeting late in the night, you enter, the terrorist by your side. There was bloodshed outside the room, other soldiers of 141 injured and bleeding by your hands. The Captain prays that it's just a ploy, just so that you could convince Hassan you were on his side.
The team freezes, all without their weapons, and all at your mercy.
".. Yer alive?!" Ghost exclaims, only for you to point you gun at him warningly.