Standard Missile-2 (SM-2)

Systems: ,

SM-2The Standard Missile-2 (SM-2) missiles were developed to provide air and cruise missile defense as part of the Aegis combat system on United States Navy ships. It was developed as the extended range version of the Standard Missile-1 surface-to-air missile, that had replaced the Terrier and Tartar missiles. The Standard Missile series emphasized modularity in design to make upgrading the missiles easier as technology developed. 1

SM-2 interceptors are solid-fueled and tail controlled, designed to launch from either MK 41 Vertical Launch Systems (VLS) or MK 26 Guided Missile Launching System (GMLS). Most versions of the SM-2 are designed to engage high-speed, high-altitude anti-ship cruise missiles (ASCM) with midcourse guidance and radar support from the ship’s systems to help illuminate the target during the terminal intercept phase. 2

The SM-2 Block II-IV are long-range interceptors that extend the battle space for commanders to engage target objects. Each missile uses semi-active radar homing and has a blast-fragment warhead with a radar and contact fuse. 3

SM-2 Block II

The Block II upgraded the original SM-2 interceptor with a signal processor to harden the system against electronic warfare systems. It also featured an upgraded fuse and focused-blast fragment to the warhead to improve the missile’s capacity to intercept smaller, harder targets. The Block II also featured new propulsion systems for higher velocities and better maneuverability allowing it to effectively integrate more radar data for accuracy. 4

SM-2 Block III

The currently deployed Block III series of interceptors have a range of around 90 nautical miles. They are 15 feet 6 inches in length and 13.5 inches in diameter and weigh around 1,558 pounds. The Block III upgrades focused on developing an advanced capability against lower altitude targets and entered service in 1981. The Block IIIA variant extends the range of the interceptor to even lower altitudes than the standard Block III interceptor. 5 The Block IIIB incorporated the infrared guidance system tested in the Missile Homing Improvement Program (MHIP) to complement the system’s radio frequency terminal homing systems and entered service in 2008. 6 This dual capability was designed to counter developments in electronic warfare.

SM-2 Block IV

The Block IV Extended Range variant can intercept targets at 100 to 200 nautical miles and are 21 feet 6 inches long, 21 inches wide with their boosters, and weigh 3,225 pounds apiece. The Block IV upgrade added a limited capability for terminal ballistic missile defense to the Block II and III capabilities against aircraft and ASCM. It entered service in 2004 and can only be deployed on Aegis ships with VLS tubes. As of 2012, the Navy had an inventory of 72 Block IV interceptors, which were created by modifying existing SM-2 missiles for ballistic missile defense. Three of these have been used in testing. 7 The Block IV features modifications to the interceptor’s fuse and autopilot. More extensive modernization was planned for the SM-2 Block IVA, which would have featured a similar dual infrared guidance system to the Block IIIB. 8

In 2015, an unspecified number of SM-2 missiles were declared Wartime Use Only after a July 18 launch incident that damaged the USS Sullivans (DDG-68). 9 The failure of the Block IIIA caused the Navy to reexamine all of the SM-2 missiles with Mk 104 Mod 2 Dual Thrust Rocket Motors (DTRM) to determine what caused the failure. The SM-2 is in service with the United States Navy as well as 15 other allied navies, though the United States plans to phase out the interceptor in favor of the SM-6. 10

In October 2016, the USS Mason (DDG-87) fired two SM-2 Block IV interceptors and one ESSM in self-defense against three anti-ship cruise missiles fired by Houthi militias in southern Yemen.


  1. “RIM-66 / RIM-67 Standard Missile – SM-1 / SM-2 / SM-3,”, 2016,
  2. “SM-2 RIM-66 / RIM-67 Standard Missile,”, 2016,
  3. United States Navy, “United States Navy Fact File: Standard Missile,” January 12, 2016,
  4. Global Security, “SM-2 RIM-66 / RIM-67 Standard Missile.”
  5. Ibid.
  6. Eric Heginbotham, “The U.S.-China Military Scorecard: Forces, Geography, and the Evolving Balance of Power 1996-2017,” RAND Corp., 2015,, Santa Monica, California: RAND Corporation.
  7. Ronald O’Rourke, Navy Aegis Ballistic Missile Defense (BMD) Program: Background and Issues for Congress (Washington D.C.: Congressional Research Service:2015),
  8. “Aegis Ballistic Missile Defense Interceptors (SM-3, SM-2 Block IV, and SM-6)”, May 2, 2012,
  9. Sam LaGrone, “Navy Restricts Use of ‘A Number’ of SM-2 Missiles Following USS The Sullivans Launch Failure,” USNI News, July 27, 2015,
  10. United States Navy, 2016.