White smoke grenades serve a very specific purpose with the U.S. military – designating landing zones for aircraft.
Smoke grenades serve a number of different functions with the U.S. military. They typically provide a "smoke screen" for soldiers and vehicles that are moving around dangerous combat zones. Modern smoke grenades are also used to block infrared sensors and laser targets. And, smoke grenades are frequently used to communicate among military personnel on battlefields.
There are many different colours of smoke grenades - red, purple, orange, yellow, blue, green and black. The coloured smoke is used to identify friendly troops and signal the location of enemy targets. These markers are important to soldiers under fire and combat stress, and can help minimize mistakes made in battle.
However, white smoke grenades are used specifically to identify landing zones for military airplanes and helicopters. The white smoke is used for ground-to-ground and ground-to-air communication between soldiers and pilots in various aircraft. The white smoke is used to signal where aircraft should touch down in a combat zone – basically a landing zone marking device. The white smoke can also help shield aircraft from enemy fire as they approach the ground and land on dangerous battlefields.