Snipers are trained for the detection, identification, and location of a targeted soldier in sufficient detail to permit the effective employment of lethal and non-lethal means. Since most kills in modern warfare are by crew-served weapons, reconnaissance is one of the most effective uses of snipers. They use their aerobic conditioning, infiltration skills and excellent long-distance observation equipment (optical scopes) and tactics to approach and observe the enemy. In this role, their rules of engagement typically let them shoot at high-value targets of opportunity, such as enemy officers.