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(CNN) -- British Prime Minister Tony Blair launched plans Monday for a new multibillion-dollar submarine-based nuclear missile defense system, warning lawmakers the future may hold perilous threats from rogue regimes and state-sponsored terrorists. The replacement fleet would cost around £20 billion.
9: The number of countries thought to have nuclear weapons, including the five formally declared nuclear weapons states -- the U.S., Russia, China, France and Britain -- and four others thought to have such arms -- India, Pakistan, Israel and North Korea.
160: Blair said Britain would cut back on its stock of nuclear warheads from 200 to 160 -- a move intended to make the proposal more acceptable to detractors within his own party.
1994: The year that Britain's first Trident submarine, the HMS Vanguard, went on a maiden patrol.
2022: The year in which the existing submarine fleet will be phased out, according to British defense officials.
$150.6 billion: the amount that opponents of the replacement system -- including nuclear disarmament campaigners -- claim the new fleet is likely to cost.
14: The number of years the British government says it will take to design, commission and build the submarines.
2: Of the nuclear powers, the U.S. and Russia, have submarine, air and land-based capability.
The government says it will take 14 years to design and build new submarines.