Rush is a new game mode to Battlefield Play4Free but can be found in other Battlefield titles such a Bad Company 2 or Battlefield 3.
Your objective is simple. Your task as the US team is to tear down the enemy forces and dispose of the Russian M-COM stations to prevent them calling in re-enforcements. Take down their M-COM stations 1 by 1 and push them out of the area for good to secure your influence in the region.
As the Russian team it is up to you to make sure that doesn't happen. Hold back your enemies and disarm any armed M-COM stations.