Russia Insider reports that the ambush on the Russian U-24 bomber was guided by the US Airforce.
In an interview with the Russian news agency Regnum, a Russian military expert said that “A US Air Force Boeing E-3 Sentry AWACS plane took off on 24 November from the Preveza airbase in Greece.
A second E-3A of the Saudi Arabian air force took off from the Riyadh airbase.
Both planes were executing a common task—determining the precise location of Russian aircraft. It is they that picked the “victim.”
The American E-3A was supposed to determine the activity of the Su-24M2′s onboard targeting radar, to determine if it was in search mode or if it had already locked on to a target and was processing launch-data. It is known that the AWACS can direct the activity of aircraft in battle, conveying information to their avionics and flight computers.
The expert went on explaining the technical details of how the US and Saudi AF planes guided the Turkish F-16s to a sure missile launch in ‘target illumination’ mode, meaning that the radar was turned off as soon as the missile locket into its target.
A U.S. Air Force Boeing E-3 Sentry AWACS plane took off on 24 November from the Preveza airbase in Greece. A second E-3A of the Saudi Arabian air force took off from the Riyadh airbase. Both planes were executing a common task—determining the precise location of Russian aircraft. It is they that picked the “victim.”
The American E-3A was supposed to determine the activity of the Su-24M2’s onboard targeting radar, to determine if it was in search mode or if it had already locked on to a target and was processing launch data. It is known that the AWACS can direct the activity of aircraft in battle, conveying information to their avionics and flight computers.

https://syrianfreepress.wordpress.com/2015/12/04/usa-guided-su-24-attack/