How independent is Britain's Trident deterrent?

Would a breakdown in US-UK relations compromise Britain's independent use of Trident?

Not immediately: Britain controls operations and launch authority, but long-term independence would require replacing shared American missile-servicing and French warhead-support facilities.

British command and control is described as operationally separate, including each prime minister's sealed instructions for a submarine cut off after national destruction. Trident navigation does not depend on GPS, and the patrol force can receive launch orders through national systems. The dependence lies chiefly in peacetime sustainment: missile servicing is shared with the United States and warhead support with France. Britain retains relevant personnel and could build replacement facilities, but successive governments have accepted shared physical infrastructure to reduce cost.