The S-400 has “limited BMD capability” it has been in comparison with Patriot, specifically the PAC-3 MSE and not even the PAC-2 and GEM-T. Virtually all my comparisons of SM-6 with S-400 have been about their performance against aerodynamic targets, stressing the difference between the two long-range SAMs: 40N6 and SM-6 in that particular role. If anyone were to compare the BMD capability of the S-400 and Aegis then he’d be looking at the SM-3.
A good insight into the complications of using fragmentation warheads for BMD roles and why countries went with hit-to-kill kinetic warheads. This, however, doesn’t mean that an interceptor with a fragmentation warhead can’t be reasonably effective in the BMD role.
Take Patriot’s performance in Saudi Arabia for example, between 2015 and mid-2019, Patriot batteries in Saudi service intercepted more than 230 Iranian ballistic missiles – that’s more than 1 intercept every week and highlighted the volume of ballistic missile they faced. By 2021, Saudi Arabia reported Patriot PAC-2 intercepted 430 Houthi’s ballistic missiles and 851 drones in 6 years that resulted in 59 civilian casualties.
For context, during Iran-Iraq war the very first Iraqi Scud killed 21 Iranians. In all, Iraq launched 189 Scuds throughout the conflict that killed 2,000 Iranians and injured another 6,000 while forcing a quarter of Tehran’s popular to flee the city. So it isn’t far fetched to call Patriot being quite effective in Saudi Arabia, having dealt with an order of magnitude more ballistic missiles than any other Air Defence system in the world. This is all the while using older PAC-2 GEM-T interceptors with fragmentation warheads.
Despite having the most extensive combat record, this doesn’t make PAC-2 comparable to PAC-3 as far as Ballistic Missile Defence is concerned. The PAC-3 because of its kinetic warhead along with Ka-band seeker offering better target discrimination and superior acceleration will be much more effective than PAC-2 and any SAM of S-400 family.
This is a big problem for any land based BMD system operating in an urban environment, but not so much for a Sea-based Terminal Missile Defence like SM-6. The odds of a missile debris from an interception hitting any member of the CSG in the open ocean is negligible. Secondly, the type of warhead is one big but nonetheless only one factor. There’s also the range of radar and overall, quality of fire-control solution. The SM-6 enjoys the advantage of being guided by SPY-1D(v) radar on Aegis ships that’s designed to provide targeting solution against suborbital Mach 24+ targets for SM-3. The SPY-1D literally has 4 times greater range than S-400’s Fire-control radar (92N6E).
Almaz-Antey claims S-400’s 92N6E radar has a 185 km tracking range against a 0.4 m^2 ballistic target. That gives an S-400 battery about 65 seconds to engage a Mach 8 class ballistic missile.
The caveat here is that 0.4 m^2 used by the manufacturer is an unrealistic RCS for a RV whose RCS ranges between 0.1 to 0.01 m^2 depending on the type. This suddenly change things as 92N6E’s range now decreases down to 130 km and 73 km respectively.
The SPY-1D has 310 km range against 0.03 m^2 target. So now the S-400 has between 46 to 25 seconds to engage a short-range ballistic missile, which to put it isn’t great.
And the S-400’s real-world tracking range doesn’t quite live up to the brochure figure as clearly demonstrated in Ukraine with S-400’s inability to handle Mach 2.5 class GMLRS rockets despite having more than >90 seconds engagement window on paper. If it has so much trouble handling Mach 2.5 GMLRS rockets which can be detected from boost-phase (with much bigger RCS), how well do you think S-400 would fare against much faster ballistic targets with roughly similar RCS?
Threat detection, tracking and Targeting solution are the first steps in Missile Defence. It doesn’t matter how good your SAMs are if it’s backed by a crappy radar system. If S-400’s large 92N6E X-band radar has so much trouble tracking a RV, how well do you think the tiny seeker-head on 48N6E3 and 40N6 SAMs would fare? The most common type of missile, the 48N6E series doesn’t even have active guidance and continue to rely on semi-active radar homing (SARH) which puts them at a distinct disadvantage against a ballistic missile (or Hypersonic target) compared to the likes of SM-6 with active-guidance and a dual-mode seeker (combining active-homing with ship-based target illumination). None of the S-400’s missiles are known to have dual-mode seekers.
Despite being a two-stage missile with a large booster (that gets separated) the SM-6 still weighs less than the single-stage 48N6E3 (1,500 vs. 1,800 kg). This corresponds to SM-6 having far greater maneuverability resulting in much better accuracy and possibly greater acceleration, a fact also highlighted by 48N6E3 carrying 3 times bigger warhead in order to compensate for its poor accuracy (180 kg vs. 64 kg). All long-range missiles of S-400 (48N6E & 40N6) suffer from the exact problem.
A large warhead will not compensate for a missile detonating at significantly longer distances from a ballistic missile (poor accuracy) since the size of the shrapnel cloud doesn’t work well against a RV hardened to withstand re-entry into the atmosphere. It just makes reliably intercepting ballistic missiles far more difficult. You need a greater density of shrapnel cloud as one achieved by a close detonation (greater accuracy) to actually damage the RV, something the SM-6 is much better at. Only the smaller 9M96E2 missiles of S-400 have comparable maneuverability of SM-6, the problem however is that they’re short-ranged (120 km) and it’s questionable how well their relatively small seeker will be able to acquire a Mach 8+ RV given the horrible performance to size ratio of Russian radars.
Lastly, you seemingly ignore the fact SM-6 is backed by the most powerful Naval Fire-control radar and a system that has been consistently optimized for Missile Defence for last 20+ years. Unlike the S-400, the Aegis platform can track the RV from a far greater range and use this information to prepare a much more comprehensive firing solution for the SM-6 while having the luxury to fine-tune that firing solution for launching another round of SM-6 should the first fail.
To date, the Aegis BMD program has had 52 live-fire tests as part of system design and modernization effort with every test being more challenging than the previous one. Since 2015 the SM-6 have been in 6 live-fire tests without a single failure. Of these, four were against Medium-range ballistic missile (MRBMs), including those with MaRV simulating AShBM.
How many live-fire tests did the S-400 program have involving a ballistic missile? Is there a published test record, never mind the class of ballistic missiles used in the test?
Even forgetting S-400’s short reaction time, don’t you think it’s a little disingenuous to put SM-6 with an established test record at the same place as the S-400 with little to no record?
the SM-6 has better BMD capability because there’s an actual test record backing it up unlike the S-400 having very little real-world data to backup the brochure claims. And when confronted with real world, the S-400 like most Russian wonder weapons didn’t quite live upto the hype. As pro-Russian Commander in Eastern Ukraine Igor Girkin puts it: The S-400/S-300V have been barely able to handle tactical ballistic missiles like single-stage Tochka-U (120 km).
The S-400’s dismal performance against ballistic missiles not to mention, S-400 does not integrate with other air defense system except Pantsir short-range missile. Russia managed to shoot down its own Su-35 and Su-34 fighter bombers in the Ukraine war. The lack of identification friend or foe (IFF) and datalink were two primary reasons the Russian air force did not operate in a formation and operating within occupied territories of Ukraine. The Russian military lacks networking and a common datalink amongst forces creating communication barriers for multi-domain operations in the Ukraine war.
Captured Russian pilot Andrey Fedorchukov told Ukrainian officials that RuAF distributed Garmin GPS and Pronebo mobile app to navigate in Ukraine because of the poor quality of Russia’s inaccurate GLONASS guidance system.
The S-400 will seriously struggle to defend against Tactical ballistic missiles while having abysmal performance against Short-range ballistic missiles (SRBM), and Medium-range ballistic missiles (MRBM) are frankly way beyond it. The SM-6 on the other hand appears to be very effective against MRBMs and it should be, after all that has always been the core design objective.
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