The S-300

Recent news that Russian leader Vladimir Putin will deliver S-300 missiles to Iran has raised concerns that the US, Israel or other nations would lose any ability to use military force to delay, degrade or eliminate Iran’s pursuit of a nuclear weapons program. Setting aside the political aspects for a moment, let us take a look at the dreaded S-300 Surface to Air Missile System (SAM).

The Russians have had a robust SAM development program just as long as the United States, and arguably had better results than the US. The Russian S-25 (NATO reporting name SA-1) Berkut and S-75 (SA-2) Dvina SAMs were roughly analogous to the US Nike Ajax, and the S-125 (SA-3) Neva was analogous the US HAWK missile. Similarly, the S-200 (SA-5) Angara fulfilled a role much as the US Nike Hercules.

A historical aside- the Soviet Union had two distinct air defense organizations. The first V-PVO, the Soviet Air Defense Forces, was a separate military service dedicated to the air defense of the Soviet Union, with its own interceptors and surface to air missile systems, and associated warning and control systems. The second was The Air Defense of Ground Troops, which was similar in mission to our own US Army Air Defense Artillery. Obviously the needs of the two forces were quite different, and so each service tended to pursue different missile systems.

That’s important, because when we talk about the S-300 SAM system, it’s important to realize that there are two entirely distinct families of S-300 with vastly different capabilities.  The S-300V family is a national defense asset. The system that Iran has purchased, and which Moscow seems ready to deliver, is the S-300P family, originally designed to protect Soviet forces in the field.

Watching US forces in Vietnam, and Israeli forces in the Yom Kippur war learn to negate the early generation Soviet SAMs through jamming and Wild Weasel tactics, the Soviet Union began development of what would become the S-300 families.  Prime objectives were better mobility for the system, to allow “shoot and scoot” capability, longer missile range, better kinematics (energy and maneuverability) for the missile, greater rate of fire, increased resistance to jamming and other ECM, and reduced vulnerability to anti-radiation missiles that homed in on the SAM battery radar.

When the Soviet Union began developing the next generation of SAMS in the 1970s, several related areas were seeing significant advancements in the state of the art, such as integrated circuits and solid state electronics, reliable digital computers for signal processing and data management, improvements in solid rocket motors, and a shift from mechanically scanned radars to phased arrays.

Let’s talk about the organization of SAM units. The basic unit is the battery, which is a roughly company sized organization, and is the smallest unit capable of independently completing an engagement. That is, it has the resources to acquire, track, identify, and engage a target. This in effect means that each battery has a command post, an acquisition (or search) radar, an engagement radar, and one or more Transporter, Erector, Launch (TEL) vehicles which hold the actual SAMs themselves.  Typically, a battery would have three TELs, each with four launch tubes, for twelve missiles. Usually two missiles are tasked to each target, so a battery can normally engage six targets before it needs to reload. Typically, two to five batteries are integrated into a battalion to cover an even wider area.

The S-300P, manufactured by Almaz, was first fielded in the late 1970s and known in the West as the SA-10 Grumble. As noted, a battery consisted of a command post, an acquisition radar, and engagement radar, and usually three TELs.

Each of the four elements is integrated to the S-300P system, but over time, each of the four elements was also upgraded, or even replaced to enhance the capability of the system. For instance, the original engagement radar, the Flap Lid (5N63), has given way to the Tomb Stone* (30N6) radar. Improvements in one element improve the overall system. And over the course of the life of the S-300P, pretty much every element has been upgraded or replaced by an improved system, to such effect that modern S-300P systems are in effect completely different systems from the original, though care has been taken to ensure backward compatibility.

Iran originally ordered S-300P in for delivery in 2008, but UN imposed sanctions, while not explicitly barring delivery, have to this point led Russia to hold off from closing the deal.  Reportedly, the Iranians will receive the S-300PMU1, also known as the SA-20A Gargoyle A.

Let’s take a look at the elements of the SA-20A.


The command post is the 54K6E.

Note the antenna for data link connection to the radars and TELs of the battery, though it can also be connected via cable.

While the system sold to Iran is reportedly the SA-20A, exactly which radars associated with the sale are included are something of a mystery. And the Russians have a vast array of, well, arrays available to chose from. One high end system is the 64N6E Big Bird.

The Big Bird is a large passively scanned phased array. In fact, the array is larger than the arrays of an Aegis radar on a US destroyer. Normally the Big Bird scans in azimuth by mechanically rotating the array, and scans in elevation by electronic beam steering. It can stop the rotation, and scan a sector of 60~90 degrees azimuth by electronic beam steering. Detection range against high flying fighter sized targets is credited as being around 150 miles. Of course, due to the earth’s curvature and the resulting radar horizon, detection range versus low altitude targets is much shorter. Consequently, many S-300P systems also use a dedicated radar for low altitude search. The radar horizon issue persists, but the radar is optimized for operating in the ground clutter environment. One such radar is the 76N6E Clam Shell.

The engagement radar is likely the 30N6E Tomb Stone phased array radar.

Rather than emitting one beam and rotating to move the beam, a phased array uses thousands of phase shifters mounted in an array (hence the name) to electronically steer the main search beam, and can also simultaneously transmit and receive secondary beams. For instance, it might be searching its engagement sector, while simultaneously also tracking half a dozen targets for engagement. It is also frequency agile, so the targets being tracked don’t receive a continuous stream of energy at the same frequency, making it harder for the target to realize it is under attack, and further, making it much more difficult to jam.

The SA-20A missile itself is the 48N6, a large, single stage missile quite similar to our own early Patriot missile. The SA-20A is cold launched vertically from a four tube launcher mounted either on a truck or semi trailer.

It is generally credited with an effective range of anywhere from 40 to 80 miles versus an aerial target. It has a maximum speed of about Mach 6, though the average speed, particularly for longer range engagements, is more typically around Mach 2 or Mach 2.5. In addition to engaging aircraft and cruise missiles, it has a limited capability against short ranged ballistic missile type targets.

The SA-20A uses a guidance technique known as Track Via Missile, or TVM. There are a couple different variations on TVM, but most work generally the same. Let’s walk through a hypothetical engagement to show how TVM works.

  1. The Big Ben acquisition radar detects a target in the battery’s sector.
  2. The target is displayed on the command posts scopes.
  3. The command post initiates the engagement by queuing the Tomb Stone engagement radar to lock onto the target.
  4. The Command post tasks a TEL to engage, and gives the 48N6 missile’s autopilot initial steering commands to follow.
  5. The missile launches vertically, then tips over to the direction of the estimated intercept point.
  6. As the missile flies toward the target, the Tomb Stone uses a radar beam to illuminate the target.
  7. A passive radar receiver in the missile receives the reflected radar energy from the target, and transmits that information in a coded stream back to the Tomb Stone radar.
  8. The Tomb Stone radar sends that message to the command post.
  9. Fire direction computers in the command post generate steering commands for the missile, and transmit them to the Tomb Stone radar.
  10. While still illuminating the target, the Tomb Stone radar also sends the coded steering commands to the missile, which generally has a receiver antenna in the back of the missile’s fins.
  11. The missile corrects its flight path.

Note that as the missile gets closer to the target, it is receiving ever more of the reflected radar energy from the target. In essence, it gets more accurate as it gets closer. TVM means that the illumination beam doesn’t need to be as powerful as a conventional semi-active homing system. Further, the missile can be somewhat cheaper, as the computing power is not on board the missile, but in the command post.



Cold Launch doesn’t always work as planned.


While the SA-20A has a formidable low altitude capability, it is optimized for the mid to high altitude counter-air role.** Since the US has, since the end of the Vietnam War, tended to operate at those altitudes to avoid low technology defenses such as gunfire and short range IR guided missiles, that poses a challenge for the US and other nations with a similar operational philosophy.

That the S-300P is a formidable air defense system is without question. But can we (or more likely, the Israelis, or less likely, the Saudis) penetrate to a target defended by it.

Well, yes, but…

As we’ve seen in air campaigns from the 1982 Israeli-Syria Bekka Valley war through Desert Storm, and Allied Force in Kosovo, the first phase of a campaign is to disintegrate the enemy Integrated Air Defense System. Some of that can be as simple as putting a Tomahawk cruise missile in the headquarter of the enemy’s air defense organization. Other weapons used to suppress or destroy air defense assets can include the Army’s ATACMs short range ballistic guided missile system. The problem is that precise targeting is needed to attack a system such as the S-300P. The S-300P can be moved in as little as five minutes. So the targeting has to be in virtually real time. To do that requires an investment in quite a few electronic warfare aircraft or other system. Once found, simply attacking it is a challenge. The maximum range of the SA-20A is nominally greater than the range of the HARM anti-radar missile normally used to attack SAM systems.

But the US, and its allies, tend to eschew taking a system versus system approach, and instead use multiple avenues to address any single platform. For instance, attacking any target protected by an S-300P would almost certainly involve significant numbers of electronic warfare aircraft, such as the EA-18G Growler, both for locating the SAM site, and for jamming the associated radars, as well as launching HARMs at them. Other supporting HARM shooters would also be used.

Other stand-off weapons targeted in real time would include the Joint Stand-Off Weapon and likely the Small Diameter Bomb, both conceived of in part to defeat long range SAM systems. All these weapons would be used on coordination with a swarm of Miniature Air Launched Decoys.

A promotional video explaining how multiple weapons can be used to overwhelm advanced SAM defenses:


Bottom line, while the S-300P system in Iran would not preclude the US or its allies penetrating defended airspace, it would make such a task much more difficult, and likely time consuming. It would also greatly increase the risk of crew losses or captured airmen.

Having said that, if the alternative is a nuclear armed Iran, it seems that risking treasure and lives is worth it.



* Current Russian designation systems are somewhat impenetrable to my mind, so I’ve tended to mostly use the NATO Reporting Name for a given system.

**It is also quite typical for an SA-20A battery to have a modern short range air defense system such as the Tor-M1 (SA-15 Gauntlet)  co-located for terminal defense of the battery itself.