The waters of the ocean under 700 metres comprise an immense volume of space which has hitherto been relatively unexploited for military purposes. Marine technology has now opened up this space and the under lying sea-bed, making it available for both mobile and fixed weapons systems to be developed for operation from such locations. Such a development is desirable for the superpowers (USA, USSR) as a means of securing complete invulnerability for their strategic deterrence forces. From a military point of view, the advantage of this environment is that it is opaque to most forms of electromagnetic radiation and the vast spaces provide considerable room for manoeuvre; its use would enable the superpowers to keep their 'second strike' or 'assured destruction' capability secure under most conceivable circumstances.
Current under-sea weaponry consists of nuclear submarine-launched ballistic missiles (SLBMs). Over 100 submarines, principally from the superpowers, were known to be in operation in the 1980s. They carried over 1,000 missiles, many of them of MIRV design.