It has long been recognized that in warfare, the best advantage available is surprise. If one can approach an enemy undetected, the attack has a better chance of being successful. The widespread use of radar starting in World War II greatly decreased the possibility of surprise for an airborne assault. Planes could be detected from miles away, giving the enemy a chance to prepare for the attack. Over the years, the military has employed many different approaches to solve this problem. The most recent development is "Stealth" technology. Stealth planes are painted with radar-absorbing paint, and designed in such a way as to minimize the number of angular surfaces from which an enemy can bounce a radar signal. The engines are also hooded to reduce the plane's heat signature. The result is an aircraft capable of approaching an enemy target, launching an attack, and returning to base with little chance of detection. The F-117A Stealth Fighter was used with great effectiveness by US forces in the Persian Gulf War in 1991.