The Iskander (left) and the ATACMS (right), two of the most capable Short Range/Tactical Ballistic Missiles are some of the target candidates for the A1A anti-ballistic interceptor.

The A1 Interceptor — A “Monster” 10 ton Warhead and Its Target Candidates — Part III

The A1 warhead

Dumitru Popescu
Commercial ECOROCKET
5 min readJan 22, 2024

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The core philosophy of the A1 anti-ballistic and hypersonic missile interceptor is the capability to intercept incoming threats without a need for precise tracking. Thus, it is immune to countermeasures and any kind of avoidance manoeuvring the target could undertake.

This is possible due to the use of a passive warhead that is activated electromechanically at a pre-programmed altitude.

The A1 interceptor warhead is probably the heaviest ever mounted on an anti-missile defence system.

Instead of explosives, or a single large kinetic warhead, it contains a large amount of metallic pellets, chaff and flare, that are deployed mechanically.

The A1A warhead

The A1A contains up to 2,000,000 pellets, chaff and flare. Their weight, composition and deployment pattern are confidential. The pellets act as kinetic projectiles, while the chaff and flare aim to distract the incoming missiles.

The estimated impact energy of one pellet deployed by the A1A is between 25–130kJ in the case of an ICBM deployed MIRV, or 12–100kJ in the case of a hypersonic missile.

A1B warhead

The A1B contains up to 20,000,000 pellets. Their weight, composition and the deployment pattern are confidential.

Because the A1B needs to defend a larger area, and is deployed at a higher altitude where the target travels at higher speeds, the pellets are significantly smaller than those used with the A1A.

The estimated impact energy of one pellet deployed by the A1B is between 1.5–5kJ in the case of an ICBM deployed MIRV, or 0.4–2.6kJ in the case of a hypersonic missile.

Some of the projectiles found in the A1 warheads.

Target candidates

Reentry Vehicles (RVs)

RVs are transported to the target by ICBMs, IRBMs, or MRBMs. Each RV is equipped with a nuclear warhead, and rarely with a conventional warhead. Frequently, ballistic missiles are equipped with MIRVs. These vehicles contain multiple independent RVs that can be deployed at the same time or released from the missile bus at various times during the flight path.

The ICBM-carried RVs reenter the atmosphere at speeds of up to Mach 24 and start to slowly decelerate as they go through the atmosphere, starting at altitudes of around 40km.

Depending on the carrier rocket type, the impact velocity of modern nuclear warheads is in the range of Mach 4–7.

The modern French, Russian and US RVs are equipped with nuclear warheads of up to 500 kiloton (and sometimes 1 megaton).

The MIRV-ed Yars ICBM during launch.

However, there are a few exceptions like the Chinese and Indian ICBMs, equipped with warheads of up to 3 megaton needed to compensate for their higher CEP (Circular Error Probable).

Depending on the nature of their target, nuclear warheads detonate above the target (air burst) and some detonate at impact or below ground.

Impact detonations are preferred in the case of hardened, underground targets.

In the case of impact, the detonation probability increases as it avoids the use of electro-mechanical detonation devices susceptible to radiation, other countermeasures or just battlefield difficult conditions generated for instance by a previous nuclear strike (fratricide).

The Minuteman III ICBM, during launch. The missile is usually equipped equipped with the Mark 12 Reentry Vehicle and the W78 nuclear warhead.

In regard to nuclear warheads only, the A1A interceptor is designed to defend against ground detonations, while the A1B interceptor is designed to defend against air burst warheads with yields up to 500 kiloton.

For the most common nuclear warheads with yields of up to 500 kilotons, the optimum detonation altitude is around 1,600m.

Short Range Ballistic Missiles (SRBMs)

SRBMs can use both conventional and nuclear warheads.

Except for cluster munition warheads when deployment can occur at altitudes of around 1,500m, the warhead remains with the SRBM from launch to delivery, and no separation occurs like in the case of larger ballistic missiles.

Therefore, the SRBM and its warhead crash into the target at the same time.

While the SRBM nuclear warhead could detonate at higher altitude, the conventional warhead (except for the cluster munition one), always detonates at impact or in the very close proximity of the target (10–20m).

The Iskander Short Range Ballistic Missile (SRBM).

The impact speed of SRBMs is usually below Mach 3.

While a kinetic kill or a catastrophic failure of an SRBM going through the A1A defensive cloud is probable, the cloud may also deceive its fuse to detonate at a significantly higher distance from the target.

Hypersonic Missiles (HMs)

While an RV usually flies to the target at hypersonic speeds, up to the warhead detonation, on a ballistic trajectory, an HM is defined by its capability to manoeuvre to avoid detection and interception.

HMs may carry both conventional and nuclear warheads, and those may separate from the missile or stay with the it until detonation, depending on the missile type.

The Kh-47M2 Kinzhal operational hypersonic missile underneath a MiG-31K fighter jet.

This rocket technology has been developed in the past decades mostly in China, India and Russia, but the US has recently made efforts to catch up. The impact speed of HM is usually up to Mach 6.

Supersonic Cruise Missiles (SCMs)

The Cruise Missiles (CM) are well developed weapons and saw massive deployment in conflicts from the past decades.

Their warheads may be conventional or nuclear. Conventional warheads are designed to detonate on impact or in the very close proximity of the target, with the exception of cluster munition delivery. Nuclear warheads may also detonate on impact, in close proximity to the ground, or (rarely) at higher altitudes.

Due to its low flight speed, a CM is vulnerable to air defences and therefore avoids flying at high altitudes to prevent detection as much as possible. Therefore, CMs are less suited to cluster munition dispersion or nuclear air burst from significantly high altitudes.

However, in the past decade we saw an increase in CM capability through the development of Supersonic Cruise Missiles (SCM). These fly at low altitude but supersonic speeds, which significantly increases their survivability.

In the case of SCMs however, the A1 interceptor remains highly efficient, as it uses the high speed of the incoming target to its advantage.

Brahmos, supersonic cruise missile.

Stay tuned as we are going to talk about the A1 interceptor’s defended areas definition and combat deployment.

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