NEW DELHI: In yet another indicator of the rapidly growing Indo-Israel defence relationship, the government has decided to purchase long-range ‘‘Aerostat Programmable Radars’’ from Tel Aviv, according to sources.

The Aerostat radars, which basically include sensors mounted on blimp-like large balloons tethered to the ground with long cables, are a long-standing requirement of the IAF. These radars, along with AWACS (Airborne Warning and Control Systems), will help bolster India’s air defence capabilities.

Indian officials are hopeful of getting at least three Israeli Phalcon early warning radar systems in the near future. Indian AWACS, as per plans, will have the Phalcon systems mounted on the Russian Ilyushin-76 heavy transport military aircraft.

Moreover, India also plans to procure more Unmanned Aerial Vehicles (UAVs) from Israel, as also look at its Arrow anti-missile systems.

Experts say air defence capabilities are primarily based on early detection and consequent destruction of enemy aircraft and missiles.

Apart from augmentation of surface-based radars, India needs a mix of airborne surveillance systems which include the more expensive fixed-wing sensors like AWACS and cheaper platforms in the shape of Aerostat radars.

AWACS and Aerostat radars can act as major force-multipliers by detecting and tracking cruise missiles and low-flying aircraft much earlier than ground-based radars, which can then be targeted by air defence systems.

They can prove decisive during aerial combat operations by effectively positioning air defence fighters against hostile aircraft. AWACS, Aerostat radars and UAVs all act as ‘‘eyes in the sky’’ to increase the ‘‘situational awareness’’ of the theatre commander.

The phased array radars on Aerostats can be operated either in a 360 degree search mode or a sector scan mode. ‘‘Aerostat radars, which can stay afloat round-the-clock for four to five weeks at one go, are much cheaper and easier to operate than AWACS. They provide three-dimensional low-altitude coverage,’’ says an expert.

Moreover, they are not too easy to shoot down. With matching internal and external pressures, Aerostats can withstand several punctures and stay afloat. They can also be reeled in, repaired and then deployed once again.

Experts say in the long term, India will have to erect an effective theatre missile defence system, with an overlapping network of early-warning sensors, command posts and anti-missile land-and sea-based missile batteries.