No country wants war, but when the inevitable is upon it then a nation should not only be prepared to attack the enemy but must also be able to defend its territory.
Having an arsenal of missiles capable of striking long distances does serve as a deterrent but an effective shield to stop incoming missiles is also key for nation's defence.
A Ballistic Missile Defence (BMD) is a system that is designed to intercept and destroy an incoming ballistic missile on its trajectory much before it approaches the target. Theoretically, a hostile missile can be intercepted at launch point, mid-course (flight through space), or terminal phase (during atmospheric descent).
Inherent problems with BMDs
Practically speaking, the first option is almost ruled out as it is would be next to impossible to know where the missile is being launched till the time it is launched. A country needs to have high level of intelligence gathering capabilities with moles in the top chain of command of the enemy to know exactly when and where a missile launch would take place. This seems highly improbable as the know how of a missile launch is known only to topmost generals.
Intercepting a missile in next two phases of its flight seem like a plausible option but one needs to bear in mind that the speed of a ballistic missile is just too high for systems to predict its precise location and path. Most of the BMDs and Anti-Ballistic Missile systems in the world aim at blocking the missile in these two phases with the focus more being on intercepting missile's ballistic trajectory outside the atmosphere.
Other theories such as confusing the missile's navigation system with jammers have been proposed, but modern ICBM's are equipped with decoys and stealth coatings to counter this.
Several countries such as Russia, Israel, China and the US claim to have BDM system in place. India is now only the fourth country after Russia, Israel and the US to have successfully test a BMD system.
Indian Ballistic Missile Defence Programme
India has a two-tier homegrown interceptor missiles system to block hostile aerial attacks. The double tiered system consists of Prithvi Defence Vehicle (PDV), capable of destroying incoming targets at high altitude, while the Advanced Air Defence (AAD) Missile for lower altitude interception.
The system is designed so that incoming missiles can be tracked and destroyed both inside (endo) and outside (exo) the earth's atmosphere.
Prior to PDV, the Prithvi Air Defence (PAD) missile was tested in November 2006, followed by the AAD in December 2007. While the PDV is designed to take out the target missile at altitudes above 150 km, the AAD is an endo-atmospheric interceptor that can engage hostile missiles at an altitude of 30 km
As per reports, both systems have been test fired 13 times since 2006. The recent test firing of PDV on February 11, 2017, was deemed to a successful one. AAD was also fired successfully on Mrch 1, 2017.
The DRDO has two phases of the BMD systems. Phase-I of BMD system is geared towards tackling enemy missiles with a 2,000-km range. Phase-II will enable interception of missiles in 5,000-km range.
Phase 1 of India's BMD is said to be ready for deployment in major cities. Phase -2 will be ready in a couple of years.
Components of India's BMD:
Prithvi Defence Vehicle
Prithvi Air Defence or PAD interceptor is a two-stage missile with interception altitude ranging between 50-80 kms.
Advanced Air Defence
Advanced Air Defence or AAD interceptor is a single-stage, solid-fuelled missile capable of intercepting incoming missile at around 30 kms.
Take off view of AAD Endo-Atmospheric Interceptor Missile
The interceptors are guided by high accuracy Inertial Navigation System (INS) and supported by a Redundant Micro Navigation System (RMNS). The interceptors zero in on the hostile missile with the help of infrared (IR) seeker and inertial guidance.
Target Missile used by DRDO
Swordfish Long Range Tracking Radar (LRTR) is a long-range tracking radar specifically developed to counter ballistic missile threat. Its main function is target acquisition of incoming missile and provide guidance to interceptors (PAD and AAD) to hit its target in space. This radar has a range of over 800 km and can be used for tracking trajectories. India is upgrading this radar to increase its range to 1500 km.
Effectiveness against cruise and ballistic missiles:
India's BMD is essentially focussed on thwarting ballistic missiles. The speed of cruise missiles is much slower than ballistic missile so defending against an attack by a cruise missile is similar to tackling low-flying manned aircraft.
DRDO Chief, Dr V K Saraswat had, in an interview, said, "Our studies have indicated that AAD will be able to handle a cruise missile intercept."