I NOTE your report on the failure of the North Korean medium-range missile launch (“North Korean missile fails only seconds after launch”, The Herald, April 17). There has been speculation from the likes of Sir Malcolm Rifkind that the failure is down to US sabotage. This far from fanciful assertion exposes that notion that (our) "independent deterrent" is neither.

Sir Malcolm’s assumption is in fact not new. It has been common currency that the US has for some time had the ability to interfere remotely with the avionics of North Korean missiles.

Sir Malcolm’s assertion is very credible, as is the fact that the United States could easily ensure that the UK could not fire its nukes without US permission. If they did so they would be, at the very least, disabled and possibly even re-directed.

It is a fact that the UK does not own any Trident missiles. Although the Trafalgar class subs are British, the missiles are the property of Uncle Sam. They are rented from the US. The warheads are "sort of" British as they are copies of the US W76 warhead.

On a regular basis the missiles themselves are sent "home" to Kings Bay, Georgia, for reconditioning. There is one source pool of Trident missiles and a sufficiency of same are doled out to the Royal Navy. They all have serial numbers and during the life of a missile it will find itself for a time aboard one the Royal Navy's four Traflagar class SSBNs (Ship, Submersible, Ballistic, Nuclear) and at another time aboard one of the US Navy's 14 Ohio class SSBNs.

The notion that the US Navy will not have, over a period of time, taken the opportunity to develop override software is simply incredible. Indeed, looked at from the perspective of the US Senates Armed Forced Committee not to take the opportunity so to do would properly be seen as an act of treason against the USA by the US Navy's top brass.

Bill Ramsay,

84 Albert Avenue, Glasgow.