Video: PM: 'Foolish to abandon Trident' David Cameron visited crew from the HMS Victorious, one of the Royal Navy's Vanguard-class submarines, in the west of Scotland, to welcome home a submarine crew from their 100th patrol. Mr Cameron used the opportunity to reiterate his belief that we should replace Trident saying potential threats from countries such as Iran and North Korea meant it could not be scaled back. His comments put him at odds with his Liberal Democrat coalition partners who want to find a cheaper alternative to Britain's multi-billion pound submarine-based Trident nuclear missile system to try to save money at a time when the nation's finances are mired in debt. A Trident renewal decision will not be taken until after the next 2015 general election, but the fact that Britain's four Vanguard class nuclear submarines reach the end of their service lives in the 2020s means it cannot be put off for long.