The Pegasus-class hydrofoils were a series of fast attack patrol boats employed by the United States Navy. They were in service from 1977 until 1993. These hydrofoils carried the designation "PHM" for "Patrol Hydrofoil, Missile." The Pegasus-class vessels were originally intended for NATO operations in the North Sea and Baltic Sea. Subsequently, participation by other NATO navies, including Germany and Italy, ceased and the U.S. Navy proceeded to procure six PHMs, which were highly successful in conducting coastal operations, such as narcotics interdiction and coastal patrol, in the Caribbean basin.

A patrol boat is a relatively small naval vessel generally designed for coastal defence, border security, or law enforcement. There are many designs for patrol boats, and they generally range in size. They may be operated by a nation's navy, coast guard, police, or customs, and may be intended for marine, estuarine, or river environments.