Opposition Infantry.
Opposition Soldiers are, predictably, members of the ambiguous group known at first only as The Opposition. The Opposition is presumably from the future beyond Kronotek, which is reflected in the Opposition's use of force fields and futuristic weaponry. Opposition soldiers are encountered in some scripted sequences, the Pompeii level, and any instance where more than two blue aura soldiers have been killed, creating a detectable distortion in the time-line that Opposition troops come to investigate.
When the player first encounters them they use DNGr pistols and they appear in a group. It is confirmed that before "The Trap" the player can kill them but it is very difficult. Later on in the game the Opposition soldiers will begin to appear equipped with M7 Rifles and Shotguns.
Despite their menacing appearance and supposed advanced technology, Opposition soldiers are easily dispatched with any form of automatic weapon, particularly with just a few bursts to the face. Their weapons, while ostensibly superior to what Kronotek possesses, are still entirely projectile based and only benefit from the addition of a tactical scope. Nevertheless, it is common for players to intentionally kill blue aura soldiers to entice the Opposition into attacking them, and then looting their futuristic rifles or pistols where such weapons are otherwise unavailable.
It is important to note that when blue aura soldiers are killed and Opposition troops warp in, all other units (friend or foe) will freeze in place, with a greenish tint covering the screen. It is impossible to kill any of the frozen men when this happens, and when the Opposition troops are defeated time will be restored and the player will be placed back where he was standing when he originally killed the blue aura soldier. Each time this occurs in a level, the number of opposition troops will increase by one indefinitely.
They have a stronger class which are only encountered a few times; the Opposition Heavy Soldiers.