UGM 96 Trident I

The UGM-96 Trident I, or Trident C4, was an American submarine-launched ballistic missile, 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 It was retired in 2005, having been replaced by the Trident II. In 1980, the Royal Navy requested Trident I missiles under the Polaris Sales Agreement; in 1982, this was changed to Trident IIs. It was the first Trident (missile) to enter service.

The Trident I is a three-stage, solid-fuelled missile.

The first eight Ohio-class submarines were armed with Trident I missiles. Twelve James Madison- and Benjamin Franklin-class submarines were also retrofitted with Trident I missiles, which replaced older Poseidon missiles.