They aren't Tier 1; this isn't special ops. They are contractors; this is Private Military Company.
A brand new faction - Private Military Company - reports in and enlarges the already enormous scope of Arma.
One year after British and coalition armed forces successfully quelled the insurgent uprising in Takistan, the NATO Green Sea deployment is in the process of a strategic drawdown of its combat troops in the region. Private military contractors shoulder the burden of the increased workload, with competition rising between the multinational organisations for lucrative security contracts. Private Military Company, ION, Inc. (formerly Black Element), successfully bid for a contract - codenamed Black Gauntlet - to provide security for a UN investigation team as they seek to piece together information regarding Takistan's abandoned nuclear weapons programme...
Arma 2: PMC, a new addon for Arma 2: Operation Arrowhead, will feature: • New playable faction - Private Military Company • Original singleplayer campaign with strong storyline unfolding across more than ten missions • Fully implemented 2 player co-op mode • New map featuring abandoned wasteland style military weapons test range environment, built upon brand new models and textures • Unique new character models • Exotic new weapons (AA-12, fully modelled XM8 variants) • Detailed new vehicles (Ka-60 'Kasatka', Armed Helicopter UAV, Armoured SUV) • Numerous new engine updgrades, including full Shotgun Ballistics Modelling and in-game Video Playback