The United States is developing its first new nuclear warhead programme in nearly four decades. The new W93 warhead, paired with the Mk7 reentry body, is now moving into the next stage of development for the US Navy’s submarine launched ballistic missile force.The US Navy said on that the W93/Mk7 programme has entered the Engineering and Manufacturing Development phase after achieving Milestone B earlier this year.The Navy described it as the first US nuclear warhead and reentry system programme initiated in nearly four decades, marking a major step in the modernisation of the sea based leg of the US nuclear deterrent.Vice Admiral Douglas Williams, director of the Navy’s Portfolio Acquisition Executive Strategic Systems Programs, said the W93/Mk7 is intended to provide flexibility and adaptability for future warfighter requirements while supporting an uninterrupted at sea nuclear deterrent.The Navy said the programme has been advanced through cooperation between Strategic Systems Programs, the National Nuclear Security Administration and industry partners.The last new US nuclear warhead to enter the stockpile was the W88 in 1988. The warhead is deployed with the Navy’s Trident II D5 submarine launched ballistic missile system and has since undergone the W88 Alt 370 modernisation programme.What are is nuclear warhead and reentry vehicle?A nuclear warhead is the part of a missile that carries the nuclear explosive. It is the warhead that produces the nuclear explosion when it reaches its target.A reentry vehicle is the protective body around the warhead. A ballistic missile can travel outside the atmosphere before heading back towards Earth. During this return, it faces extremely high temperatures and pressure. The reentry vehicle protects the warhead during this stage and helps deliver it towards its target.In the W93/Mk7 programme, the W93 is the nuclear warhead, while the Mk7 is the reentry body that carries and protects it. The two are being developed together for the US Navy’s submarine launched ballistic missile force.How the W93 will be usedThe W93/Mk7 is being developed for the US Navy’s Trident II D5 submarine-launched ballistic missile system. The Trident II D5 currently carries the Navy’s W76 and W88 nuclear warheads, with the warheads housed inside reentry bodies.The Navy says the future D5 Life Extension 2 (D5LE2) system will incorporate the new W93/Mk7 alongside the existing W76 and W88 families.The missiles are currently deployed aboard the Navy’s 14 Ohio-class ballistic missile submarines. Each operational Ohio-class SSBN is limited to 20 Trident II D5 missiles, after four of its original 24 missile tubes were permanently deactivated.Each Trident II D5 is a multiple-warhead missile, meaning a single missile can release more than one independently targeted reentry vehicle.
