Since 1945, there have been 2119 recorded nuclear weapons tests. The United States has conducted the most tests with 1032, followed by the USSR with 727. The Tsar Bomba, a 50-megaton hydrogen bomb detonated by the Soviet Union in 1961, was the largest device ever exploded. This massive detonation created a fireball that reached nearly the altitude of the release plane and was visible from nearly 1,000 kilometers away. The resulting mushroom cloud extended over 64 kilometers high, well into the mesosphere. Buildings in a village 55 kilometers from ground zero were completely destroyed. Wooden houses were destroyed and stone structures damaged hundreds of kilometers away. The thermal pulse could cause third-degree burns up to 100 kilometers from the blast site. A shock wave was observed 700 kilometers away, and window panes were broken up to 900 kilometers. Atmospheric focusing caused further damage, breaking windows in Norway and Finland. The seismic shock circled the Earth multiple times. The last recorded nuclear test before an update was by North Korea in 2013, with further tests conducted in 2017.