Defence minister Al Carns quit tonight as he accused Labour of 'failing' Britain's armed forces, saying he could not 'in good conscience' back the Defence Investment Plan. The Armed Forces minister followed his boss, defence secretary John Healey, out of the door as he said the long-delayed document was 'not built for the threat we face'. The latest resignation by the decorated former marine was swiftly followed by an announcement from Number 10 that Dan Jarvis would be replacing Healey as the new defence secretary. Sir Keir Starmer insisted in his first statement since the crisis began on Thursday that the Government would 'give our armed forces the capabilities they need to defend Britain and keep our nation secure'. Al Carns said in his resignation letter to the PM: 'We owe those who serve the UK the kit to do the job and the loyalty to stand by them when it's done. We are failing on both.' He added that he could not stand up in Parliament and defend 'a level of investment I know to be inadequate to the task.' 'We are asking our armed forces to operate in a more dangerous world on a budget written for a calmer one,' he said. 'A serious country funds its defence to meet the threat it actually faces, not the threat it wished it faced.'