The National Defense Service Medal is a military decoration of the United States military and was the brainchild of President Dwight D. Eisenhower. Created in 1953, the National Defense Service Medal was intended to be a “blanket campaign medal” issued to any member of the United States military who served in a designated time period of which a “national emergency” had been declared.

In the fifty years since the creation of the National Defense Service Medal, it has been authorized for the following time periods.

• June 27, 1950 to July 27, 1954 for service during the Korean War
• January 1, 1961 to August 14, 1974 for service during the Vietnam War
• August 2, 1990 to November 30, 1995 for service during the Gulf War
• September 11, 2001 to a date to be announced for service during the War on Terrorism

The National Defense Service Medal is awarded to anyone who serves on active duty in the United States military during the above time periods. For service in the Gulf War and War on Terrorism, it is also authorized for members of the military reserve provided they are a “military reservist in good standing.” This infers that a reservist must be in a drill status and also be participating in regular annual training. The National Defense Service Medal is further authorized to students at the service academies, but is not granted to discharged or retired veterans who did not serve in one of the above time periods. The decoration is also not authorized to members of the inactive reserve.

Since the National Defense Service Medal has no other award criteria, except that a recipient must simply join the military, it is generally considered a rather insignificant decoration. Common phrases for the award include the “Hear Thunder and See Lightning Medal”, the "Fireguard Ribbon" (referring to the nightly fire watches performed during basic training), "The Cheeseburger Ribbon" (referring to the ribbon's yellow stripe), or the "Firewatch Ribbon" (common phrase in the Marine Corps).

There is also not a time limit imposed for the medals issuance, meaning that someone who joins the military for simply a few days, and then receives an entry level discharge, would technically be entitled to the National Defense Service Medal.

Multiple awards of the National Defense Service Medal are authorized for members of the military who served in more than one of the eligible time periods; such additional awards are denoted by service stars. A second award of the medal is not granted for reenlisting during the same time period or transferring between branches of service.