August 23, 2012: Thailand has ordered another nine RIM-162 ESSM (Evolved Sea Sparrow Missiles), as well as three MK25 Quad Pack canisters, some training, spare parts, and maintenance gear. The missiles and associated equipment are for a Thai frigate (a modified Type 053 class frigate) obtained from China twenty years ago. This ship had largely Western weapons and electronics installed.

Fourteen years after it was introduced the U.S. ESSM is also available in a land based version. The U.S. Navy and fourteen foreign customers already use ESSM on their warships and several are interested in the land based model.

ESSM is a modified version of the standard Sea Sparrow shipboard anti-aircraft missile, which has been around since the late 1970s. Sea Sparrow was based on the 1950s era U.S. Air Force AIM-7 Sparrow radar guided air-to-air missile. That weapon, much modified and upgraded, is still in use. ESSM is basically a new missile, being different in shape and capabilities from the original Sparrow. ESSM can track and destroy high-speed anti-ship missiles and small, fast attack boats, as well as aircraft.

ESSM is 3.7 meters (12 feet) long, has a diameter of 254mm, and weighs 280 kg (620 pounds). It carries a 39 kg (86 pound) blast fragmentation warhead, has a range of 50 kilometers, and a top speed of 4,210 kilometers an hour. Guidance is provided by the firing ship's radar, which directs the missile to the general area of the target. At that point the ESSM missile uses its own guidance system, which homes in on the ship's radar signals bouncing off the target. The land version will be able to use one of various ground based radars.

The ESSM on ships is usually stored and fired from a MK25 Quad Pack canister, each holding four missiles. Each of these MK25s will fit into one VLS (Vertical Launch Systems) cell. Each ESSM costs less than $500,000.