Balkan war is test site for US hi-tech planes

The US is using the Nato operation in Bosnia to continue tests of a high-altitude surveillance aircraft that has not been used in action since the Gulf war five years ago, writes Christopher Bellamy.

The device may be used to monitor the withdrawal of troops from areas to be handed over under the Dayton peace plan.

The Joint Surveillance Target and Attack Radar System, or "Jstars", produced the spectacular radar images of the Gulf war battlefield which showed Iraqi forces streaming northwards towards the Euphrates, the first time a great battle had been captured in its entirety in pictures.

The US is continuing to test two Jstars planes over the much more difficult landscape of Bosnia, with its steep valleys, mountains and forest - the ultimate test of the system.

The use of Jstars over Bosnia has another potential advantage. The US has been trying to sell Jstars to Nato for years. Using it over Bosnia as part of the Nato operation, Joint Endeavour, will be a strong selling point.

The alternatives are a British system, called Astor (Airborne Stand-Off Radar), the French Horizon, or the Italian Creso.Jstars and Astor are the only systems capable of monitoring an entire theatre of operations. Astor will be more advanced, but is not yet even in the development phase.

Jstars would be used to monitor "vehicle-type movements" in Bosnia. Under the Dayton agreement, Bosnian Serb, Muslim and Croat forces are to withdraw from areas to be transferred to other parties by 3 February. The new owners are to occupy them by 20 March.

Jstars can look out to a range of 200 nautical miles, so it can stay outside the range of surface-to-air missiles. It even has a memory to keep track of strings of vehicles and wait for them to reappear out of a valley or from behind a mountain.

"If a convoy disappears [Jstars] will alert you," a Northrop Grumann official said. "It has a memory. It knows where to look." Two of the E- 8 Jstars aircraft - converted Boeing 707s - left the testing grounds of Northrop-Grumann in Melbourne, Florida, for Bosnia on 14 December. The US Air Force has a requirement for 20 Jstars systems, to be bought over the next 10 years at a total cost of $5bn (pounds 3.2bn) to $7bn.

Jstars can receive pictures from E-3 Airborne Warning and Control System (Awacs) aircraft. Jstars, therefore, will be used to home in on contacts - for example, helicopter flights picked up by Awacs - as well as for closer analysis of events on the ground.