Thousands have gathered in central London at a rally against the renewal of the U.K.'s Trident nuclear weapons system.SNP leader Nicola Sturgeon and Labour leader Jeremy Corbyn also attended the protest organized by the Campaign for Nuclear Disarmament (CND) Saturday.Thousands carried placards reading "NHS not Trident", "Cut War Not Welfare" and "Homes not Trident" marched from Marble Arch to Trafalgar Square. They also chanted slogans against renewal of the weapons system.Sturgeon told Anadolu Agency that this was an opportunity to make their voices heard. "Trident should not be renewed, Trident should be scraped," she said.CND Vice President Bruce Kent said there is "no argument" for the project."Public opinion is actually against spending 150 billion pounds [$208 billion] or more in nuclear weapons," Kent added.Roger McKenzie, assistant general-secretary at UNISON, emphasized that government spending had other priorities like the NHS and public services.Trident is the U.K.'s sea-based nuclear weapons system comprised of three parts: submarines, missiles and warheads. There are four trident submarines.It was introduced in the 1990s and is based in the river Clyde in Scotland; hence, the crucial importance of the SNP's anti-nuclear deterrence position.Political divisions revolve around two main issues: how many submarines Britain should have and how this affects "continuous at sea deterrence", or the ability to always have a nuclear-armed vessel on patrol.The government claimed in 2013 that the Trident would cost between £15 billion ($20.8 billion) and £20 billion ($27.75 billion), but Greenpeace said that once running and extra costs are taken into account, the bill runs to at least £34 billion ($47 billion).