Battle your way to Volk's hideout and download his master plan
For the initial sequence, use your grenade launcher to take out the enemies and enemy vehicles. Keep doing this until you've reached the target's hideout.
Once there kill the enemies along the way then drop a flash grenade before taking the ladder down to avoid ambushed below.
Clear the tunnel first before moving forth, then carefully make your way to the basement where the mainframe is located. Before planting the bug to download the data, make sure both weapons are fully reloaded and pick up some claymores on the nearby table. Set them up along the two possible enemy routes (stairs and the tunnel) – just make sure not to place them close together. You may want to replace your secondary primary weapon with either the shotgun or the light machine gun.
Defend your position until the download is complete. Once done, pick up one Riot Shield then fight your way back up. Along the tunnel, there will be a Juggernaut waiting so lob all your grenades from a distance to soften him up, then use flash riot shield melee to take him out. Continue fighting your way up and ride your vehicle to complete the mission.