Main Page | See live article | Alphabetical index A submarine-launched missile (SM) is missile fired from a submarine. Some SMs are placed within launch capsules and can be fired through the submarine's torpedo tubes. These missiles are initially propelled by a solid propellant motor and once clear of the water (and the launch capsule) they then ignite the boost motor. See also Submarine launched ballistic missile. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.