Tough call on Colonel Ngo! Those are all three pretty solid in my mind.
Winters looks too young.
Neither uniform seems right for Nguyen.
I think the second one for Gearing works better, and not just because it looks like he's trying to conceal a tissue sample in one hand... :D
For Halawi, while "Asa" can be a boy's or girl's name, it seems to be more strongly associated with males. That said, the first picture's head is too big for his body.