For the past 10 years, the Royal Navy has sent a nuclear powered submarine to patrol the waters east of Suez, near Somalia, Yemen and Iran.
The BBC's defence correspondent Jonathan Beale has been given exclusive access to one of those submarines on its return journey home after 10 months at sea.
Petty officer Paul Farran told Jonathan Beale that they do not have any communication with the outside world, except for a 38-word message from the family which they receive every week from home.
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