Early on, Sayid clashes with Sawyer, who accuses him of being a terrorist. Sayid then reveals that he is a veteran military officer who saw service in the Gulf War.
Albeit in the Iraqi Republican Guard...
With his background in communications, Sayid's skills could be invaluable in the survivors' rescue plans - a fact quickly recognised by Jack, who includes him in his leadership circle.
But is Sayid communicating all the facts about himself? Perhaps Sawyer's early suspicions about Sayid are nearer the truth than anyone realises...