A rocket propelled grenade (RPG) is a shoulder-launched, anti-tank weapon system. It consists of a rocket-propelled explosive warhead and a launcher which is operated by one or two people. The warhead is typically fitted with an impact-detonating fuse, which triggers the explosive when it hits a target. RPGs are generally unguided weapons, but some variants can be guided with the use of a laser or infrared sight. RPGs were first developed in the Soviet Union during World War II and remain in use today by many military forces around the world. The RPG is an effective weapon for close combat, as it can fire directly at a target without the need for line-of-sight or direct fire, which makes it useful against tanks, bunkers, and other hard targets. It is also relatively easy to use and can be fired from various positions, including from the ground or from a rooftop. Despite its effectiveness, the RPG is considered to be an indiscriminate weapon and its use in populated areas can cause significant civilian casualties.