Small Fuze – Big Effect

“It is not true,” British Defence Secretary Des Browne insisted during an interview with BBC radio, that a new fuze planned for British nuclear warheads and reported by the Guardian will increase their military capability. The plan to replace the fuze “was reported to the [Parliament’s] Select Committee in 2005 and is not an upgrading of the system; it is merely making sure that the system works to its maximum efficiency,” Mr. Browne says.

The minister is either being ignorant or economical with the truth. According to numerous statements made by US officials over the past decade, the very purpose of replacing the fuze is – in stark contrast to Mr. Browne’s assurance – to give the weapon improved military capabilities it did not have before.

The matter, which is controversial now because Britain is debating whether to build a new generation of nuclear-armed submarines, concerns the Mk4 reentry vehicle on Trident D5 missiles deployed on British (and US) ballistic missile submarines. The cone-shaped Mk4 contains the nuclear explosive package itself and is designed to protect it from the fierce heat created during reentry of the Earth’s atmosphere toward the target. A small fuze at the tip of the Mk4 measures the altitude and detonates the explosive package at the right “height of burst” to create the maximum pressure to ensure destruction of the target. The new fuze will increase the “maximum efficiency” significantly and give the British Trident submarines hard target kill capability for the first time.
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