An anti-nuclear protest which blocked the Faslane Naval Base on the Clyde has led to the arrest of 21 campaigners.
The submarines are armed with Trident nuclear missiles
The demonstration by members of Trident Ploughshares began at 0700 GMT. A main route to the base, the A814, was blocked for more than an hour.
Activists chained themselves together at entrances to the base which is home to the Trident missile system.
The protest comes after Prime Minister Tony Blair set out plans to build a new generation of nuclear submarines.
The prime minister said retention of the nuclear deterrent was "crucial" to national security.
A Trident Ploughshares spokesman said: "Our government, far from honestly moving towards disarmament, is planning to tie us to weapons of mass destruction for the next 50 years.
"We must do what we can to put a spoke in the wheel of this ongoing crime."