October 2, 2026: Early in the war, Russia used many S-400 SAM (Surface-to-Air Missile) systems to protect its forces and the bases located on the Russian side of the Ukrainian border. In theory, S-400 should be able to protect itself from any aerial threat, including high-speed ballistic missiles. Ukrainian tactics against S-400s involve using the ATACMS missiles they received from the United States. Most ATACMS have a range of 300 kilometers, while some have a range of 165 kilometers. Ukrainians are using the 300-kilometer version, which can change its trajectory after launch and deploys hundreds of bomblets over the target.

The ATACMS long-range version’s mid-flight trajectory change breaks any target lock Russian SAM radars, including the S-400, have on it, leaving them too little time to reacquire the ATACMS warhead and lock on. Plus, the S-400 radar does not detect ATACMS bomblets because they are too small. The bomblets land in a large area and manage to destroy the S-400 radar, the fire control operator's truck as well as several missile launchers, each containing four missiles, The ATACMS also manages to avoid getting shot down by an S-400 missile by at least a dozen drones being sent in first and, as the S-400 was shooting down drones, at least five ATACMS were launched to release 300 or 800 bomblets over the target area, where the S-400 battery was deployed. These tactics destroyed an S-400 system situated too close to the Ukrainian border. Normally, S-400 batteries are based further to the rear, but the Russians wanted to take out aerial targets farther inside Ukraine and positioned this S-400 battery too close to the front line to protect itself from Ukrainian tactics.

Russia began the war with fifty S-400 batteries. By mid-2024, about a quarter of those batteries were destroyed or severely damaged. Russia has had to remove S-400 batteries protecting areas deeper inside Russia and move them closer to prevent Ukrainian warplanes, especially the new American F-16s, from being a problem, and to shoot down the growing number of missiles being fired at Russian targets. This led the Ukrainians to develop tactics that destroy operational S-400 batteries, making Ukrainian airspace dangerous for Ukrainian aircraft or Ukrainian missiles fired at Russian targets.

Ukrainians were not the first to discover how to deceive and destroy S-400 air defense batteries. In 2018, Russia announced that the last component of the S-400 SAM system, the 40N6 long-range 400-kilometer missile, had been accepted into service and that it planned to build a thousand of them. Russia currently has 41 battalions/batteries; both terms are used, with at least 330 operational truck-mounted launchers. What makes a group of launchers, usually 4-8, a battery is the search radar and command center. After twenty years of development, all the initially specified components of the S-400 system are in service.

The S-400 is advertised as the most modern and cost-effective SAM system available. An S-400 battery sells for about half the price of a comparable American Patriot battery. The major difference between the Patriot and the S-400 is not price or specifications, but combat experience. The S-400 has none, and the Patriot has lots and is gaining more every month in Saudi Arabia and Israel. The S-400 is attractive to buyers because it looks good and costs a lot less than combat-proven systems. Another major factor is crew quality and the training they receive, as well as the capabilities of air defense commanders who decide how SAM systems are used, and the ability of commanders and their crews to quickly adapt to enemy capabilities and tactics.

Patriot export customers get experienced and demanding instructors. If their students don't try or aren't trainable for one reason or another, Americans will make an issue of it because Patriot performance depends on crew effectiveness. Russia is more understanding of such problems. Russia can provide skilled, exacting instructors but will back off if the customer isn't willing to pay for that level of instruction. If crews end up poorly prepared to handle S-400 in action, Russia will also quietly provide Russian crews who will be called something else, like maintenance advisors, but stand ready to take charge if the S-400 must perform well. Russia is also accommodating when it comes to paying large sales commissions as bribes to get the sale and handle follow-up training and maintenance support. So, for many reasons a buyer would want to be publicized, the S-400 is a more attractive purchase than the Patriot. These sales tactics are nothing new for Russia and were common during the Cold War, especially when Russia was offering high-tech weapons to corrupt dictatorships who appreciated a supplier who understood their needs.

Historically, the ineptest users of Russian SAMs have been the Assad Syrians, while the most effective users of similar Western systems are the Israelis and Americans. The Saudis are building quite a record with their use of Patriot systems against Iranian-supplied ballistic missiles fired by Yemeni Shia rebels. The Saudi Patriots have shot down nearly all 100 or so Iranian and some older Russian ballistic missiles fired at Saudi Arabia. The only success the Syrians have had with the older S-200 system is shooting down a slow four-engine Russian maritime reconnaissance aircraft off the coast. The S-200 entered service in the 1960s and has been updated since. The S-300 entered service in 1978 and has had no combat experience with the Russians, though Ukraine has in this war, using Soviet-era equipment left in Ukraine after the Soviet Union collapsed. The S-400 entered service in 2007. The Syrians didn’t mean to shoot down the Russian aircraft. They were aiming at Israeli aircraft that were already back in Israel. Russia, to demonstrate how attentive it is to customer needs, agreed with the Syrians and blamed Israel even though the Russians knew exactly what happened.

Syria also holds the dubious distinction of having its Russian air defense system wiped out in 1982 by the Israelis, who suffered no losses while doing so. Those Russian air defense weapons are not really that ineffective. In 1999, Serbian crews, using some of the same systems the Syrians had, avoided destruction and even shot down an F-117 stealth aircraft by being more adaptive and imaginative than the Syrians in 1982. Two other factors are important. After the Cold War ended in 1991, the United States purchased some S-300 systems, tore some down, and got others operational for realistic testing. The U.S. shared this data with the Israelis. This showed that the S-300 was potentially effective, but much depended on the crew and their commanders.

The Russians have also learned from experience; as a result, the S-400 and later post-Cold War S-300 systems use much more automation, making them less dependent on crew skill. But the question of commander quality and commanders' ability to adapt to combat conditions remains. Finally, it is no secret that post-Cold War Russian weapons suffer from serious quality-control problems during manufacturing, and several new Russian missile and electronic systems have suffered embarrassing failures in use. No wonder the S-400s are so cheap. They are priced to sell, not actually work in combat. But in the hands of competent, adaptive users, the S-400 and other Russian systems can be far more effective than those operated by poorly trained and led operators.

An S-400 battery has eight launchers, each with two or four missiles, plus a control center and radar, and 16 missiles available as reloads. All equipment is mobile. The S-400 was originally known as the S-300PMU3, SA-21, and was renamed S-400 because it proved to be far more than another upgrade of the S-300 and was considered sufficiently different to warrant a name change.

The S-400 entered service in 2007 when the first units were deployed around Moscow. Russia claimed the S-400 could detect stealth aircraft, implying that the hypothetical enemy was the United States. Russia also claims the S-400 can knock down short-range ballistic missiles with reentry speeds of up to 5,000 meters per second, like the U.S. Patriot system. Russia immediately offered the S-400 for export, but the system's lack of combat experience hampered that effort. Patriot has knocked down aircraft and ballistic missiles; S-400 has not. Moreover, Russia's anti-aircraft missile systems have a spotty history, especially when confronted by Western electronic countermeasures. The first S-400s were based around Moscow as part of a project to rebuild the Soviet-era air defense system, which had fallen apart since the early 1990s.

During the first six years of use, between 2006 and 2012, Russia put 12 S-400 battalions into service. Before the crash in oil prices and sanctions over attacking Ukraine hit in 2014, Russia was planning to have 56 S-400 battalions in service by 2020. Budget cuts didn't hurt much, as about 40 battalions were in service by mid-2017. Even before then, the Defense Ministry ordered more older S-300V systems in 2012. This suggests the S-400 had problems; it certainly faced many delays, but those were apparently resolved. The S-400 appears to have not only matured technically but has also undergone frequent upgrades and modifications. Nevertheless, the S-400 had not yet seen combat, although it had performed well in tests.

The S-400 claims to be superior to the U.S. Patriot and is expensive by Russian standards. By 2012, Russia was pushing the S-400 as an export item, despite its advanced technology. Most S-400 missiles weigh 1.8 tons each, are 8.4 meters long, and about 50cm in diameter. The system has four missiles, each with a different range: the 9M96E is 40 kilometers, the 9M96E2 is 120 kilometers, the 48N6 is 250 kilometers, and the 40N6 is 400 kilometers. The missile has a 145.5 kg warhead. The target acquisition radar has a range of 700 kilometers. S-400 missiles can hit short-range ballistic missiles up to 60 kilometers away. Belarus and Algeria already had some S-400 equipment delivered and active. China ordered six battalions, India five, and Turkey four. Several other countries were negotiating purchase deals.

The S-400 has more range than the American Patriot's 160 kilometers, weighs twice as much, and claims far more capabilities. The S-400 anti-missile capability is limited to shorter-range ballistic missiles with incoming speeds under 3,500 kilometers per hour. That would mean a warhead coming in at about 5,000 meters per second. The longer the ballistic missile's range, the higher its re-entry speed.

The S-400 system has two types of missiles: a smaller type with ranges of 40 and 120 kilometers, and two larger missiles with much longer ranges of 250 and 400 kilometers. The 40/120-kilometer-range missiles are deployed four to a launcher, like S-300 systems. The S-400 has no experience against Western countermeasures, but U.S. intelligence believes tests these systems have undergone indicate they are capable air-defense weapons. Its true capability won't be known until it's used in combat. None of the S-300 series systems have any combat experience either, but some models have performed well in tests.

The S-400 is to be complemented and eventually replaced by the S-500. This system was perpetually stuck in development and faced several embarrassing delays. In 2009, the S-500 was declared on track to enter service in 2012. It missed that deadline, and the service date moved to 2014, then 2015; the system finally entered service in 2021. NATO knew the original S-300 during the Cold War as the SA-10. This system entered service in the late 1970s and was subsequently upgraded several times. One major upgrade was the SA-12, which entered service in the late 1980s.