You got limited time to take out all targets. The white bar indicates how long you have to complete the mission. The red bar shows how long before snipers zero in on your location. Shoot them down before they get you!
Your objective is to shoot the bad guys as accurately as possible. You can aim for the head or the body area. The closer you are to the center of each of these areas the more points you gain. The trick is to make every single shot count.
Prepare for the battle to protect your base and complete your Lone Ops by taking down enemy troops. Upgrade your artillery and special attacks as needed.