Protesters have gathered at Faslane naval base as the prime minister outlined plans to replace the Trident nuclear weapon system.
Campaigners want an end to the Trident weapons system
Tony Blair backed a new generation of nuclear weapons in a white paper published on Monday.
A small protest began at the north gate of the Clyde base at 0700 GMT.
Campaigner Dr Alan Mackinnon said: "This a weapon which we don't need, can't afford and which will exacerbate the risks it is supposed to counter."
Dr Mackinnon, who is chairman of the Scottish Campaign for Nuclear Disarmament, added: "This will be Tony Blair's legacy for Scotland - to saddle us with Britain's nuclear weapons for the next 50 years.
"Future generations will not forgive us if we roll over and allow it."
The protest was co-ordinated by the Faslane 365 campaign.