Turkey has signed a contract with US company Boeing to purchase four "airborne early warning and control system/AEWC" aircraft in a deal worth about $1.1 billion.
Under the contract Turkey will buy four Boeing 737 planes with an option to order two more. The aircraft are expected to be delivered in two to three years.
The contract was signed after lengthy negotiations with Boeing since November 2000 when Turkey made the company top of the list ahead of three other US rivals in the tender which was launched in 1998.
Turkey, which has the biggest army in NATO after the United States, its main arms supplier, originally planned to spend some $150 billion to modernise its army over the next 30 years. But severe financial turmoil in November 2000 and February 2001 has forced the postponement of a number of projects including a tender for 145 combat helicopters and another for 1,000 tanks.
Meanwhile a Turkish fighter jet on a training flight crashed in western Turkey, killing the pilot.
The F-16 jet crashed as it was coming in to land at an air base near the city of Izmir, on the Aegean coast, after experiencing engine problems, a military statement said.