The US sets the targets for UK cruise missiles. The French set the targets for French cruise missiles. The Frogs could bomb NY, the Brits, not so much...
Nitpick: the British submarines carry ICBMs (technically, SLBMs, which is mostly just an ICBM launched from a submarine), not cruise missiles.
(In case anyone is wondering what the difference is, a cruise missile is basically a suicidal unmanned drone that flies like an airplane, while an ICBM is a rocket that goes into space and then falls back down on its target after burning its fuel.)
