Template:Short description Template:Infobox weapon
The UGM-96 Trident I, or Trident C4, was an American submarine-launched ballistic missile (SLBM), built by Lockheed Martin Space Systems in Sunnyvale, California. First deployed in 1979, the Trident I replaced the Poseidon missile. It was retired in 2005, having been replaced by the Trident II.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The missile was a three-stage, solid-fuelled system, capable of carrying up to eight W76 warheads in the Mark 4 RB.
The first eight Template:Sclasss were armed with Trident I missiles. Twelve Template:Sclass- and Template:Sclasss were also retrofitted with Trident I missiles, which replaced older Poseidon missiles.
In 1980, the Royal Navy requested Trident I missiles under the Polaris Sales Agreement. In 1982, the agreement was changed to supply Trident II instead.