duration and intensity of the reaction through inertial confinement and neutron reflection. Nuclear fusion bombs can have arbitrarily high yields making them hundreds or thousands of times more powerful than nuclear fission. A pure fusion weapon is a nuclear weapon that doesn't require a primary fission stage to start a fusion reaction. Antimatter Antimatter bombs can theoretically be constructed, but antimatter is very costly to produce and hard to store safely. Other Aerial bomb Delay-action bomb Glide bomb General-purpose bomb Incendiary bomb - Incendiary bombs are designed to set targets ablaze. Cluster bomb Anti-runway penetration bomb Bunker buster Concrete bomb - A concrete bomb is an aerial bomb which contains dense, inert material (typically concrete, hence the name) instead of explosive. The target is destroyed using the kinetic energy of the falling bomb. Inert bomb An inert bomb is one whose inner energetic material has been removed or otherwise rendered harmless. Inert munitions are used in military and naval training, and they are also collected and displayed by public museums or private parties. Typically, NATO inert munitions are painted entirely in light blue and/or have the word "INERT" stenciled on them in prominent locations. IED (barrel bomb, nail bomb, pipe bomb, pressure cooker bomb, fertilizer bomb, molotov cocktail) Delivery The first air-dropped bombs were used by the Austrians in the 1849 siege of Venice. Two hundred unmanned balloons carried small bombs, although few bombs actually hit the city. The first bombing from a fixed-wing aircraft took place in 1911 when the Italians dropped bombs by hand on the Turkish lines in what is now Libya, during the Italo-Turkish War. The first large scale dropping of bombs took place during World War I starting in 1915 with the German Zeppelin airship raids on London, England, and the same war saw the invention of the first heavy bombers. One Zeppelin raid on 8 September 1915 dropped of high explosives and incendiary bombs, including one bomb that weighed . During World War II bombing became a major military feature, and a number of novel delivery methods were introduced. These included Barnes Wallis's bouncing bomb, designed to bounce across water, avoiding torpedo nets and other underwater defenses, until it reached a dam, ship, or other destination, where it would sink and explode. By the end of the war, planes such as the allied forces' Avro Lancaster were delivering with accuracy from , ten ton