'I’m announcing today new capability for the SM-6. We’re modifying the SM-6 so that in addition to missile defense it can also target enemy ships at sea at very long ranges' U.S. defense secretary Ashton Carter said at Naval Base San Diego California on February 3.

'This is a new anti-ship mode. It makes the SM-6 basically a twofer. Can shoot down airborne threats' Carter said. 'And now you can attack and destroy a ship at long range with the very same missile.'

While the long-range SM-6 was known to have an extremely potent air and missile defense capability this is the first time the Pentagon has acknowledged that the weapon has an anti-surface mode. The older shorter-range version of the Standardthe SM-2also had an anti-surface mode though it was not exactly far reaching.

The SM-6which incorporates an active radar seeker and networkingwas designed to engage targets beyond a ship's radar horizon. Using the Naval Integrated Fire Control battle network an Aegis warship could engage over-the-horizon targetsincluding aircraft cruise and ballistic missilesby using targeting data from a Northrop Grumman E-2D Advanced Hawkeye.

The physical radar horizon for a S-band radar like that of the Aegis is about 250 nautical miles for a target flying at about 30000 feet. For target flying at lower altitudes the radar detection range would be shorterwhich is where the E-2D comes in. While the range for the SM-6 is classified the weapons range could potentially be greater than 250 nautical miles.

Because the E-2D has the capability to track air and surface targets the SM-6 would effectively allow U.S. warships to engage enemy surface combatants or even swarming boats over-the-horizon with a Mach 3.5+ missile. While the SM-6's warhead was designed to kill aircraftand as such is relatively tinythe fact that it also has ballistic missile defense capability suggests it has a hit-to-kill capability. Read more