Friendly snipers can be used to hunt the enemy sniper. Besides direct observation, defending forces can use other techniques. These include calculating the trajectory of a bullet by triangulation. Traditionally, triangulation of a sniper's position was done manually, though radar-based technology has recently become available. Once located, the defenders can attempt to approach the sniper from cover and overwhelm them. The United States military is funding a project known as RedOwl (Robot Enhanced Detection Outpost With Lasers), which uses laser and acoustic sensors to determine the exact direction from which a sniper round has been fired.