The UGM-73 Poseidon missile was a US Navy nuclear-armed submarine-launched ballistic missile (SLBM) system powered by a two-stage solid-fuel rocket. The first test launch took place on 16 August 1968. By 1992, the Soviet Union had collapsed, 12 Ohio-class submarines had been commissioned, and the START I treaty had gone into effect, so the older Poseidon SSBNs were disarmed.
