MILITARY jets escorted a plane into Stansted Airport as part of a major training exercise in Essex.
Emergency procedures are being tested to make sure the county is ready should a serious disaster strike.
A spokesman for Essex Police said: "Essex Police is engaged in a safety and security exercise.
"Military jets have been deployed from RAF Coningsby as part of this exercise.
"There is no threat to the public and no need to be concerned.
"The exercise has been a year in the planning and is part of ongoing national emergency planning procedure testing."
The Home Office, Ministry of Defence, Essex Police, Essex County Fire and Rescue Service and other agencies are all taking part using airport buildings and a plane.
The Essex Police spokesman said: "This exercise forms an integral part of a national training programme and is a necessary and important test of contingency plans.
"It provides invaluable training and experience for all participants."
A spokesman for Stansted Airport said: “We can confirm that Essex Police Force and other Forces in the region, in conjunction with other responders are taking part in a multi-agency, safety and security exercise from June 11 to 13 to test major incident contingency plans.
“There is a legal responsibility under the Civil Contingencies Act to regularly test these plans through the use of an exercise.”
The exercise concludes tomorrow.