RIM-156 Standard SM-2
A member of the Standard SM missile series, the RIM-156 Standard, also known as the SM-2ER Block IV, is a long-range naval surface-to-air missile principally designed to be fired from Vertical Launch Systems (VLS) on ships equipped with the AEGIS battle management system. These include the U.S. Ticonderoga-class cruisers, Japanese Kongo-class and U.S. Burke-class destroyers, and Spanish F-100 frigates. The earlier SM-1 variants were fired from launch rails, not vertical launchers.
Its launch is controlled by the Mark 99 fire control system, its initial and midcourse guidance comes from from a AN/SPY-1 AEGIS search radar, and it uses terminal semi-active radar homing from an AN/SPG-62 illumination radar.
In a layered anti-air warfare defense, the next defense is the RIM-162 ESSM (Evolved Sea Sparrow Missile), with a range of 27+ nm/50+ km, forms the next band. For final defense, there is the 9 km (5 nm) RIM-116 Rolling Airframe Missile on ships equipped with it, or with the Phalanx close-in weapons system autocannon.
Modifications of the SM-2 are called blocks.
SM2 block IVA is a SM2 Block IIIb with a short but exceedingly powerful booster attached. Booster length was limited by the maximum length of a VLS cell. With the booster, the range extends to 150 mi. It can over-the-horizon anti-ship missile, nearly replacing Harpoon on the Ticonderoga-class, and supplanting it entirely on the Arleigh Burke-class. It has a smaller warhead than the AGM-84 Harpoon, but the missile itself is much larger and faster; the total kinetic energy with the warhead is greater than that of the Harpoon. It is, however, expensive, and less maneuverable at short range than the Block IIIb; a ship may carry a mixture of the blocks.
RIM-174 Standard SM-6, is effectively a Block IV missile, to which the active radar seeker of the AIM-120C-7 AMRAAM air-to-air missile has been added for terminal guidance. Because of that seeker, the ERAM acronym, in 2008, was redefined to mean Extended Range Active Missile. The active terminal radar replaces the semi-active radar homing of the RIM-156, which now requires the AN/SPG-62 illuminator, which is not over-the-horizon-capable. 
- Function: long-range, ship-launched surface-to-air missile
- Prime contractor: Raytheon
- Length (incl. booster) 6.55 m (21 ft 6 in)
- Finspan 1.57 m (61.8 in)
- Diameter 0.34 m (13.5 in); booster: 0.53 m (21 in)
- Weight 1450 kg (3200 lb)
- Speed Mach 3.5
- Ceiling 33000 m (110000 ft)
- Range 240 km (130 nm)
- Propulsion United Techologies MK 72 solid-fueled rocket booster; Atlantic Research MK 104 dual-thrust solid-fueled rocket sustainer
- Warhead MK 125 blast-fragmentation
- "Raytheon RIM-156 Standard SM-2ER Block IV", Designation Systems