****UPDATE****

***SPOILERS WILL FOLLOW THIS SO YOU BETTER STOP HERE IF YOU DON'T WANT ANY***

Call of Duty Wikia has posted some information about this first level of the game, and from our understanding you ARE NOT playing as a terrorist, but rather an UNDERCOVER CIA AGENT who is infiltrating a Russian terrorist organization. If you continue to their article, the word is that the leader of said terrorist organization actually finds your character out as he is escaping in an ambulance, and he ends up dead...

Please read their full post for all of the details because they have worked on collecting this information a lot harder than I have. 

Here's a quote from their site:

In this level you will assaulting a Russian airport as an Undercover C.I.A Agent with Makarov's terror group.

Introduction

You will start this mission talking with the Ultranationalists. In order to stay undercover, you must do what they do. After coming out of the lift, civilians will notice you and become wary. Suddenly, your allies will mow them all down. Continue fighting through the airport killing everybody in your way. Eventually you will end up outside and be met with counter-terror police. Kill them and follow your squad. Eventually you will reach an ambulance which is your escape vehicle. Don't get carried away, you won't be going with them. As Makarov sees you escaping, he will shoot you down and escape. You are tended to by police, but you will eventually die.