Gilders had certain advantages, however. Paratroopers, soldiers landing by parachute, were usually spread over a large area. They could easily be separated from other paratroopers and from air-dropped equipment, such as vehicles and anti-tank guns. Gliders, on the other hand, could land troops and equipment precisely at the target landing area. Once released from the tow aircraft, military gliders were silent and difficult for the enemy to identify. Larger gliders were developed to land heavy equipment like anti-tank guns, anti-aircraft guns, small vehicles, such as jeeps, and also light tanks (e.g., the Tetrarch tank). This heavier equipment made glider forces much more capable. During World War II, the United States had about 6,000 trained glider pilots. Some were given a second chance to fly as glider pilots after failing to complete conventional aircraft training. The Soviets also experimented with ways to deliver light tanks by air, including the Antonov A-40, a gliding tank with detachable wings.