Ben Wallace has piled pressure on Boris Johnson and Rishi Sunak to hike defence spending to help the UK deal with the threats posed by a “less secure” world following Russia’s invasion of Ukraine.
The defence secretary said his department’s budget will need to increase from the middle of the decade.
His comments came as the prime minister conceded that the government will break its pledge to increase defence spending by 0.5 per cent above inflation every year.
Speaking at the start of the NATO summit in Madrid, Wallace said that while he had enough money for this year and next, the Treasury will need to come up with more cash for the Ministry of Defence from 2024.
He told Sky News: “If Britain wants to maintain its leadership role post-2024 we’re going to have to see greater investment.”
Wallace added: “The key for me as defence secretary is to make sure that the government appetite for using its defence forces is matched by the resources put in place.
“I’m just really keen that we recognise that my [budget] settlement was done before Russia invaded Ukraine.
“Russia is very, very dangerous now on the world stage. The world is less secure than it was two or three years ago and that is not looking likely to change for the next decade.
“I want some momentum in the middle of the decade to say we should commit to increased funding.”
Asked how much extra money he would like, Wallace replied: “Well, how long is a piece of string?”
His comments came as the prime minister prepares to tell his fellow world leaders that they must “dig deep” to increase their defence spending over the next decade.
Members of NATO are expected to spend at least two per cent of their gross domestic product on defence, a target which the UK currently meets.
But Johnson is expected to tell today’s summit: “Over the next ten years the threats around us are only going to grow. We need allies – all allies – to dig deep to restore deterrence and ensure defence in the decade ahead.
“The two per cent was always meant to be a floor, not a ceiling and allies must continue to step up in this time of crisis.
“I remain incredibly proud of the immense contribution defence makes to the UK and the world. Defence of the realm is the first order of any government. But more than that, defence lies at the beating heart of the United Kingdom.
“Almost every family knows someone who has served our country or worked in our thriving defence industry. Moments of national joy are observed from the skies by our incredible Red Arrows, moments of national mourning are flanked by our men and women in uniform.
“And as we think about crafting a future in which the people of the UK are safe and prosperous, we must again turn to defence. To neglect the needs of our Armed Forces is to neglect our country.”