It's a submarine-launched ballistic missile system comprised of the Trident missile, the special Trident warheads and the Ohio-class ballistic missile sub.

An ALBM is an air-launched ballistic missile, a ballistic missile launched from a bomber.

Trident Ballistic Missile Submarine

The Soviet Union built 4 new classes of submarine-launched ballistic missiles and over 60 new missile submarines.

The M45 submarine-launched ballistic missile was first tested in 1986. It was fired in 2004 from the Vigilant at a target near French Guinea, which it hit.