A strategic nuclear weapon refers to a nuclear weapon which is designed to be used on targets as part of a strategic plan, such as nuclear missile locations, military command centers and large cities. A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. A missile (see also pronunciation differences) is a self-propelled explosive Projectile used as a weapon towards a target They are contrasted with tactical nuclear weapons, which are designed for use in battle, as part of an attack with conventional forces. A tactical nuclear weapon (or TNW) refers to a Nuclear weapon which is designed to be used on a battlefield in military situations Strategic nuclear weapons have significantly larger yields, at least over 100 kilotons and up to many megatons. Units of mass There are three similar units of Mass called the ton: Long ton (simply ton in countries such as the United The most powerful nuclear weapon ever tested was the Tsar Bomba (about 50 megatons), detonated above Novaya Zemlya. Tsar Bomba (ru Царь-бомба literally " King Bomb" is the Western name for the RDS-220 hydrogen bomb (codenamed "Иван" (Ivan by its Novaya Zemlya (Но́вая Земля́ also spelled Novaja Zemlja, lit Yields can overlap, though, and many weapons, such as the B61 nuclear bomb, are used in both roles. The B61 Nuclear bomb is the primary Thermonuclear weapon in the U Strategic nuclear weapons also have greater range. Intercontinental ballistic missiles with nuclear warheads are strategic weapons, while short-range missiles are tactical. In addition, while tactical weapons are designed to meet battlefield objectives, the main purpose of strategic weapons is to deter attacks, especially nuclear attacks.