Marine One officially is the call sign of any U.S. Marine Corps aircraft carrying the President of the United States.

On March 1, 2009, an Internet security company from Cranberry, Pennsylvania, reported that it had discovered the blueprints for Marine One on a peer to peer file sharing network located in Tehran, Iran. The company immediately notified the federal government of the security issue. Retired General Wesley Clark, an adviser for the company, indicated that they know the exact computer the leak came from and where it went. Sources also indicated it was not leaked from government manufacturer Lockheed Martin, as was theorized by some.WPXI (Pittsburgh): Lockheed Not Source of ... Leak (March 2, 2009)

1. HMX-1 squadron formed in 1947National Geographic: On Board Marine One: Facts
2. Fleet based in Quantico, VirginiaNational Geographic: On Board Marine One: Facts
3. Secondary "alert facility" located at the Anacostia Naval StationNational Geographic: On Board Marine One: Facts
4. Quantico base maintains a K-9 unit to help with securing Marine OneNational Geographic: On Board Marine One: Facts
5. Often used as transport from the South Lawn of the Whitehouse to Andrews Air Force Base where Air Force One is based
6. First used by Dwight D. EisenhowerNational Geographic: On Board Marine One: Facts
7. Paint scheme dates back to pre-air conditioning daysNational Geographic: On Board Marine One: Facts
8. Top painted white to reflect heatNational Geographic: On Board Marine One: Facts
9. Always met on the ground by at least one Marine in full dress uniformNational Geographic: On Board Marine One: Facts
10. Always flies in a group of identical helicopters for security
11. Equipped with very sophisticated defense systems to prevent an aerial attack

The term "marine one" is also often used to describe any one of the special presidential helicopters flown by the HMX-1 Marine squadron. Current helicopters in the Marine One fleet include the Sikorsky VH-3D and the Sikorsky VH-60N Whitehawk, however both are scheduled to be replaced by a new fleet of VH-71 Kestrel choppers. Previously the U.S. Army and the U.S. Marine Corps shared the responsibilities of presidential helicopter transportation by alternating between using Army One and Marine one, however in 1976 the Marines took complete control of this duty with Marine One.

In 2005 the White House selected the Lockheed Martin VH-71 Kestrel as the replacement Marine One helicopter after a fierce battle between Lockheed Martin and Sikorsky Aircraft for the coveted contract. The $6.1 billion dollar contract for 23 helicopters was expected to be fully completed by 2014, however due to delays the total is now $11.2 billion, or roughly $400 million dollars per helicopter, and the time table will most likely be pushed back. While the new fleet of VH-71 Kestrel's will feature over double the the cabin space then the current fleet in addition to many other new benefits, but many called the contract controversial due to the fact that Lockheed Martin uses many parts not made in America. Critics argue that the American made helicopters from Sikorsky Aircraft would have been a better choice because of their record of producing Marine One since 1957.