American F-16 jets are set to tear across Jordanian skies as part of joint military exercises involving troops from the US, Britain and several Arab countries.
The so-called “Eager Lion” drills have been condemned by Russia which accuses the West of fanning the conflict in Syria with its border less then 120 kilometres away.
Jordan which has lent support to Syria’s rebels is nervous that the fighting will spill over and ignite a regional conflict.
The success last week of Syrian government forces in the routing of rebels from the key strategic city of Qusair is seen by many as a boost for the regime.
Both Russia and the US are still pushing for a Geneva peace conference, though there is still no agreed date.