A cross-channel investigation has been launched after two submarines carrying nuclear weapons – from the Royal and French navies – collided in the Atlantic. HMS Vanguard and Le Triomphant crashed on February 3 or 4, despite both vessels being equipped with sonar. The British submarine, which has a crew of 135, weighs nearly 16,000 tonnes and is 150m long, is one of Britain's four V-class subs under the Trident programme. Armed with 16 ballistic missiles, it is now believed to have been towed last night to Faslane, a nuclear submarine base in Scotland, with dents and scrapes to its hull. Its French counterpart was reportedly carrying a similar number of warheads, and also had around 130 crew on board. A senior Navy source was quoted as saying that the potential consequences of such a collision would be "unthinkable"."It’s very unlikely there would have been a nuclear explosion," the source said.