The Navy fielded active radar seekers over 40 years ago in the Phoenix air-to-air missile it procured by the thousands. The story is different for the surface fleet. In spite of this simple but important enhancement almost all of the Navy’s surface-to-air missiles do not have active radar seeking technology.

The missiles that are the mainstay of the fleet’s defensive arsenal such as Standard Missile (SM) and the Evolved SeaSparrow Missile (ESSM) are only equipped with semi-active radar homing, and where this form of homing has tactical handicaps. Semi-active homing works by having an external source illuminate a target with its radar. The radar reflections are picked up by the missile, which then finds its way to the target with the assistance of mid-course guidance from the external radar. Because a ship is limited by the horizon, if a target dives deep enough, the ship will no longer be able to illuminate it with its radar to see the engagement through.

Land-based surface-to-air missiles are not as inhibited by semi-active homing in spite of the same horizon limitation because they work in tandem with other anti-air systems. An aircraft diving low to avoid illumination over land places itself at risk of being engaged by shorter range anti-air weapons that do not reveal themselves through radar emissions. This tactic worked to great effect over Vietnam as radar-guided surface-to-air missile batteries forced American warplanes to drop altitude and fly within range of gun-based anti-air systems which ended up shooting down more aircraft than missiles. There is no similar effect at sea because capability is concentrated on warships.

To an extent Sailors already know the Standard Missile is handicapped by its guidance capability. The Standard Missile has an anti-surface mode, but of dubious effectiveness. Its range is less than 20 miles in this mode because that is only as far as the ship’s radar can target it close to the surface and to the limit of the horizon.

An annual Defense Department report from 1975 highlighted this issue when it sought to develop an anti-ship version of the Standard Missile:

“The STANDARD SSM program was initiated in 1971 to provide an interim anti-ship missile capability until the HARPOON could be developed and deployed. The STANDARD SSM is operational in two versions, with a third now in development…The third version, Active STANDARD with a radar seeker…will have a range capability beyond the ship radar horizon. The range of the STANDARD semi-active missile is limited to the range of the ship’s radar, since the missile’s target must be illuminated by a ship radar. The STANDARD ARM and Active STANDARD, equipped with an anti-radiation homing capability and an active terminal seeker, respectively, eliminate the need for illumination of the target by a ship radar and thus permit engagement of targets beyond the ship radar horizon.”

In the end the original Active Standard SSM never made it into the fleet though the same basic idea and capability would be replicated decades later. Despite many variants produced across nearly 50 years of service active radar seeking did not come to the Standard Missile family of weapons until SM-6 arrived in 2013. Even so, SM-6 does not have a unique seeker but takes its active radar seeker from the widely equipped AMRAAM air-to-air missile that entered service in 1991. SM-6 introduced an anti-ship capability in 2016, similar in concept to what was already deemed desirable many years ago in the form of the Active Standard SSM. SM-6 now bears the odd distinction of being both the Navy’s first long-range active radar seeking surface-to-air missile, and its first supersonic anti-ship missile.

In explaining the benefit of SM-6 the Navy once again described the value of similar technology 40 years later:

“The introduction (emphasis added) of active-seeker technology to air defense in the Surface Force reduces the Aegis Weapon System’s reliance on illuminators. It also provides improved performance against stream raids and targets employing advanced characteristics such as enhanced maneuverability, low-radar cross-section, improved kinematics, and advanced electronic countermeasures.”

However, SM-6 will be fielded in relatively small numbers because it is extremely expensive and is not meant to replace the more widely equipped SM-2. Active radar homing will also not come to the Evolved SeaSparrow Missile, the Navy’s main short-ranged defensive anti-air missile, until the Block 2 upgrade hits the fleet in 2020. The Navy is already pursuing a more common Standard Missile variant equipped with an active radar seeker, the SM-2 Block IIIC. The missile is being pushed through the Navy’s Maritime Accelerated Capability Office in a bid to shorten the acquisition timeline and hopefully get it into the fleet within three years.

However, according to the Navy’s 2017 program guide the Standard Missile variants that do not have active radar seekers “will be the heart of the SM-2 inventory for the next 20 years.”

The Heavy Bomber

“We think we can destroy it; it is our business to attack it, and it is up to you to judge whether we can do it or not. Give the air a chance to develop and demonstrate what it can do!”–Billy Mitchell in 1921 urging Congress to support bombing warships with planes in testing.

When combat is joined between missile-armed fleets the maneuver of individual warships will matter little in the near term because of the large disparity between ship speed and missile speed. Upon engaging in fleet combat a commander’s most flexible means to respond to risk and opportunity in timely fashion will be through speedy aviation. Despite its single-minded focus on using aviation to sink ships at range the Navy never effectively incorporated the use of heavy bombers.

Heavy bombers can feature very long endurance and range, far superior to that of carrier aircraft. Bombers also have large carrying capacity that allows them to mount a level of offensive firepower comparable to that of a warship. Because long-range anti-ship firepower usually outranges anti-air firepower by a steep margin heavy bombers can have a powerful ability to fire effectively first against warships.

Both Russia and China field heavy bombers with long-range anti-ship firepower, and where heavy bombers were at the leading edge of Soviet anti-ship capabilities throughout most of the Cold War. Soviet-era Backfire bombers can travel over 1500 miles, are capable of supersonic speed, and can fire multiple Mach 3 missiles that have hundreds of miles of range. Large Backfire bomber raids have been expected to be a principle tactic for countering American carrier groups far from Russia for decades.

Similar platforms exist within the U.S. military, but heavy bombers belong to the Air Force. It appears the Air Force bought very few Harpoon missiles with less than 100 in its inventory by the mid-90s.  The full adoption of an anti-ship role for heavy bombers may have also been hindered by a combination of inter-service rivalry between the Navy and the Air Force as well as differing priorities in their contingency planning.

Soon one of the most powerful anti-ship platforms in the American arsenal will not even belong to the U.S. Navy. The platform that will first receive the first truly modern and widespread anti-ship missile of the U.S., LRASM, will not be a Navy asset but the Air Force’s B-1 bomber. These bombers will be able to carry 24 of these powerful weapons, packing over 15 times the anti-ship firepower of a Harpoon-equipped U.S. surface warship. These planes will make for an extremely powerful asset when combined with their thousands of miles of range. This year the U.S. will finally have a heavy bomber with credible long-range anti-ship firepower, but after the Soviets pioneered the same capability half a century ago.

Shortchanged

Of the Navy’s errors in arming the fleet none can compare to failing to effectively bring its offensive firepower into the age of missile warfare. Only now is it on the verge of doing so with launch cell-compatible missiles like LRASM and the Maritime Strike Tomahawk that are just a couple years away from hitting the fleet. Finally the Navy will have widespread anti-ship firepower that can hit at over 100 miles. This wholesome introduction of long-range anti-ship missiles comes over half a century after the Soviets proved it was possible.

But this recent introduction of long-range anti-ship firepower will not be the Navy’s first attempt. Up until now much of the Navy’s story of fielding anti-ship missiles consists of developing weapons long after they were first possible, then not fielding them in effective numbers, subsequently removing them from the inventory, only to then try and reintroduce them decades later. The Navy lagged long enough to where today there are 400-ton Chinese missile boats that carry more long-range anti-ship firepower than 9,500-ton, billion-dollar American cruisers and destroyers that have around 100 launch cells.

Why was the Navy stuck with only the short-ranged Harpoon for so long, and why were competitors able to design so many more anti-ship missiles with greater lethality in the meantime?

The answer may lie with doctrine. The aircraft carrier has remained the centerpiece of U.S. Navy anti-ship doctrine since WWII. Harpoon probably became the Navy’s first anti-ship missile and remained its primary anti-ship tool for over 40 years because it appears Harpoon was one of the first anti-ship missiles small enough to fit onto multirole aircraft, such as those flown from aircraft carriers. By comparison, airborne anti-ship firepower for the Soviets mostly took the form of enormous missiles that could only be carried by large bombers. The very short range of Harpoon was made up for by the long reach of aviation that could travel hundreds of miles and strike targets well before they could get within range to unleash their own anti-ship firepower.