With the tactical nuclear weapons having been withdrawn from service, Trident was the UK's only remaining nuclear weapons system. By this time, possession of nuclear weapons had become an important part of Britain's national identity. Not renewing Trident meant that Britain would become a non-nuclear power. It would spell the end of the Special Relationship with the United States, and strike at Britain's self-image as a great power. A decision on the renewal of Trident was made on 4 December 2006. Prime Minister Tony Blair told MPs it would be "unwise and dangerous" for the UK to give up its nuclear weapons. He outlined plans to spend up to £20bn on a new generation of ballistic missile submarines. The new boats would continue to carry the Trident II D-5 missiles, but submarine numbers might be cut from four to three, and the number of nuclear warheads would be cut by 20% to 160. He said although the Cold War had ended, the UK needed nuclear weapons, as no-one could be sure another nuclear threat would not emerge in the future.