Editing UGM-27 Polaris (section)

=== Polaris A-3 ===
[[File:Polaris-Poseidon family of SLBMs.jpg|thumb|Polaris A-1 to A-3, Poseidon]]
[[File:DominicFrigateBirdPolaris.gif|thumb|Polaris A-3 [[Operation Dominic]]. Only full-scale US test of a strategic missile system.]]
This missile replaced the earlier A-1 and A-2 models in the [[U.S. Navy]], and also equipped the British Polaris force. The A-3 had a range extended to {{convert|2500|nmi|km|abbr=off}} and a new weapon bay housing three Mk 2 re-entry vehicles (ReB or Re-Entry Body in U.S. Navy and British usage); and the new W-58 warhead of 200&nbsp;[[kiloton|kt]] yield. This arrangement was originally described as a "cluster warhead" but was replaced with the term Multiple Re-Entry Vehicle (MRV). The three warheads, also known as "bomblets", were spread out in a "shotgun" like pattern above a single target and were not independently targetable (such as a [[MIRV]] missile is). The three warheads were stated to be equivalent in destructive power to a single one-megaton warhead due to their spread out pattern on the target. The first Polaris submarine outfitted with MRV A-3's was the [[USS Daniel Webster (SSBN-626)|USS ''Daniel Webster'']] in 1964.<ref>{{Cite book|title=The U.S. nuclear arsenal : a history of weapons and delivery systems since 1945|last=Polmar, Norman.|date=2009|publisher=Naval Institute Press|others=Norris, Robert S. (Robert Stan)|isbn=978-1557506818|location=Annapolis, Md.|oclc=262888426}}</ref> Later the Polaris A-3 missiles (but not the ReBs) were also given limited hardening to protect the missile electronics against [[nuclear electromagnetic pulse]] effects while in the [[boost phase]]. This was known as the A-3T ("Topsy") and was the final production model.