Sir Keir Starmer said the UK had to be prepared for war to be able to deter potential enemies as he set out the £15 billion defence investment plan.
The Prime Minister acknowledged some other areas of Government spending would be slashed in order to fund defence, with road and energy projects scrapped to pay for the military.
Sir Keir said: “When the world is arming and aggression is rising, the best way to avoid war is to prepare for it.
“The best way to defend is to deter, to have the strength to make your adversaries think again before they act.
