An attacker is confronted with three possible ways to pursue an enemy, all of which are vital during chase. "Lag pursuit" happens in a turn when the nose of the attacker's aircraft points behind an enemy's tail. Lag pursuit allows an attacker to increase or maintain range without overshooting. "Lead pursuit" in a turn occurs when the nose of the attacking aircraft points ahead of the enemy. Lead pursuit is used to decrease the distance between aircraft, and during gun attacks when the cannons must be aimed, not at where the defender is, but where he will be when the bullets get there. "Pure pursuit" happens when the nose of the attacker points directly at the defender. Pure pursuit is when most missiles will be fired, and is the hardest position to maintain. These are known as pursuit curves.