The Ohio class is a class of nuclear-powered submarines used by the United States Navy. The United States has 18 Ohio-class submarines: 14 nuclear-powered SSBNs (ballistic missile submarines) each armed with up to 24 Trident II SLBMs and 4 nuclear-powered SSGNs (cruise missile submarines), each capable of carrying 154 Tomahawk cruise missiles with either conventional or nuclear warheads.