"The table represents the state of the submarine fleets - as of 1 May 2007 - of the 43 nations that operate submarines ranging from tiny midget boats more dangerous to their own crew than to any potential target to modern diverse fleets employing the latest in undersea technologies. The fleets are listed by type of submarine and by classes, while the builder column indicates the country of origin. When two countries are listed the first is the design originator and supplier of critical components, the second is the ship's assembly site. Operational totals do not include submarines undergoing pre-operational trials or those that have been long non-operational for lack of repair or refit resources but are still listed as potential assets; these are noted in the Class and Remarks column. This column also provides additional information on the status of on-going acquisition programs and impending requirements. AIP indicates an air-independent propulsion system. The information employed in compiling the table was derived from official and authoritative unofficial sources."