The intensity of relations between the United States and Russia has reached its zenith. That has led nuclear deterrence and missile defense to once again become a relevant subject of discussion, as they were during the Cold War. I have already discussed the countries’ balance of strategic nuclear forces in a separate series of articles covering land, undersea and air components. Now it's time to pay attention to their missile-defense system capabilities and assess whether they can—at this point or in the future—shift the strategic balance towards any party’s side.

U.S. Missile Defense: Strategic GMD and Progressive Aegis

The only existing U.S. strategic missile-defense system capable of intercepting the warheads of intercontinental ballistic missiles is GMD (Ground-Based Midcourse Defense). The principle of the system is the kinetic interception of enemy warheads prior to their entry into the atmosphere. The target is destroyed by a direct hit with a small Exoatmospheric Kill Vehicle (EKV) interceptor, which is sent to the enemy warhead by the Ground-Based Interceptor (GBI) launch vehicle. The top speed to which EKV accelerates is approximately ten kilometers per second, and the speed of an ICBM warhead is approximately seven kilometers per second. Direct head-on collision at such speeds leads to the guaranteed complete destruction of any combat unit. However, the most difficult task in this situation is to successfully lock the kinetic interceptor on a target moving at great speed. At this point, eighteen test interceptions using the GMD system have been performed, with nine being successful—only 50 percent. This is despite the fact that tests are conducted in the most benign conditions; the target is known in advance and consists of a single warhead with no missile defense breaching systems. At this point, about thirty interceptors are deployed in Alaska and California, with the plan being to increase their number to forty-four by 2017. At this stage of development, GMD will be able to knock down at least twenty warheads in case of a large-scale ICBM strike. Considering that based on the New START Treaty, Russia and the United States may possess up to 1,550 strategic nuclear warheads, this figure is small and insignificant.

Another, more “flexible,” missile defense system, which may claim the label of strategic by 2022, is the Aegis Ballistic Missile Defense System, originally created in a ship-mounted modification. Now the land version—the Aegis Ashore—is being built in Romania and Poland. The Aegis BMD has a great advantage due to the placement of SM-3 missiles in the universal Mk-41 cell launchers. Not only is the Mk-41 compatible with interceptor missiles, it is also capable of launching anti-ship missiles and BGM-109 Tomahawk strategic cruise missiles. Currently the SM-3 Block IB interceptor missile is used, which is able to destroy short- and medium-range missiles at ranges of up to seven hundred kilometers. They are capable of intercepting ICBMs only at the initial stage of the flight, and given the size of Russia’s territory, and most underground missile silos and mobile units’ location far from Russia’s borders and seas, striking down the missiles at launch would be impossible. There are new versions of missiles, named the SM-3 Block IIA in development (phase-in expected in 2018) and the SM-3 Block IIB (phase-in planned for 2022). They dramatically outperform their predecessors in speed and range, which reaches 2,500 kilometers. Those new variants are likely to have the ability to destroy ICBMs warheads. In fact, they are very similar to GMD. In addition to missiles warfare, the Aegis has already proven that it is capable of effectively dealing with low-orbit satellites.

And yet, as we have already noted, the real effectiveness of ICBM warhead interception is yet very low, and initial flight-stage missile interception in the event of confrontation with Russia is inefficient (the European part of Russia holds a very small number of ICBMs—and in theory those are only possible to bring down during the launching phase). After the warhead has separated from the booster, it is practically impossible to intercept, and after separating the plurality of warheads and decoys too many interceptors are needed to repel the attack. And they are very expensive—more expensive than the warheads.

Russian Missile Defense: A-235 to Replace the A-135

Currently Russia has Moscow as a single area of ​​strategic missile defense system positioning. It is protected by the A-135 system adopted in 1990. Initially, A-135 consisted of two types of missiles: the 51T6 (ABM-4 “Gorgon” according to NATO classification) was created for long-range interception, and the close tier is defended by the 53T6 (ABM-3A “Gazelle” according to NATO classification). The 51T6, capable of destroying an ICBM warhead at a range of six hundred kilometers, was written off in 2006 due to its expiration date. The close tier is still armed. 53T6 missiles have a range of one hundred kilometers, with a height of interception of thirty kilometers; unlike the 51T6, the target is destroyed after entering the atmosphere. This anti-missile has unique characteristics allowing it to quickly respond to the threat: its maximum speed of 5.5 kilometers per second is reached in four seconds. Human vision cannot detect the movement of “Gazelle.” It intercepts ICBM warheads in, at most, twelve seconds after launching. In both interceptors, the principle of interception is very different from that in the American system, as it involves a high-altitude nuclear explosion of small capacity which does not cause any collateral damage to friendly forces. This approach allows us to raise the probability of destroying targets to almost 100 percent, because it does not require a direct hit and many of the ICBM warheads’ missile-defense breaching tools appear useless.

The extreme age of the A-135 system has led Russia to develop a replacement: the A-235 system, allegedly dubbed “Nudol.” There is no detailed and comprehensive information on the characteristics of the system yet, as it remains secret. But according to reports, the A-235 will have two or even three defense tiers. The most distant tier will be protected by interceptor missiles similar to the 51T6—but with the interception range increased to 1,000–1,500 kilometers. The nearest tier would be defended by a new modification of the 53T6, whose high-precision guidance would eliminate the requirement for nuclear warheads for interception—using instead a blast-fragmentation warhead. There is no data on the intermediate-tier missiles yet; perhaps there will none at all. In addition to ICBM warfare, the A-235 can be used against satellites and hypersonic cruise missiles. Unconfirmed information suggests that portion of the A-135’s launchers will be mobile.

U.S. and Russian TMD Systems: Getting Closer to Reality

We have reviewed the existing missile designs that are partly capable of dealing with ICBM warheads above. We will now turn to more “simple” systems, designed to combat short-range and medium-range missiles.

In the case of the United States, there are two major tactical missile defense systems. The first is THAAD (Terminal High Altitude Area Defense), performing kinetic exoatmospheric interceptions at a distance of two hundred kilometers. The second is the Patriot PAC-3 anti-aircraft missile system, capable of combating short-range missiles at an altitude of fifteen to twenty kilometers.

In Russia, there are also two main weapons systems capable of performing these tasks: the S-400 and S-300V4 antiaircraft missile systems. The latter is even more effective, as it has already received a new rocket, which allows for intercepting ballistic targets at altitudes of up to sixty kilometers and at ranges of up to four hundred kilometers. The S-400 will receive these missiles in the near future. Russian air defense missile systems are different from those of the United States, being less dependent on satellite data and having larger number of simultaneously engaged targets. And finally, Russia is actively developing the mobile S-500 anti-missile system. According to the available data, considering system capabilities, it will be similar to the Aegis when equipped with SM-3 Block IB interceptor missiles. Perhaps it will be able to combat ICBM warheads to some extent, but it is still too early to consider the S-500 a strategic missile defense system.

At this point, both the United States and Russia have achieved the capability of destroying the old Soviet short-range R-17 missiles (SS-1C Scud B according to NATO classification) with high probability. Those missiles’ simulators are used in most of the trials, and the Patriot PAC-3 took down nine of these missiles in 2003 in combat conditions. However, the R-17 has long been obsolete and used by countries access to more advanced weapons. In reality, the United States and Russia will likely go to war with these countries rather than with each other. In a hypothetical military conflict between Russia and NATO, the existing U.S. tactical missile defense system is unlikely to be able to cope with the modern Russian Iskander tactical ballistic missiles—even the probability of hitting the R-17 with two interceptor missiles is not 100 percent. Iskander is highly maneuverable, has a reduced radar signature and creates interference. It is far from certain that during a real war that even a single such missile could be destroyed.

Conclusions