The six-day Indo-US joint military air exercise began on Monday morning at the Kalaikunda Air Force station in West Midnapore district amidst protest demonstrations by Left Front activists.

Tight security measures were in place in view of the exercise, with the police putting up barricades on roads leading to the Air Force station.

IAF sources, while confirming that the joint exercise had begun, refused to give any more details.

The demonstrations have been organised by the West Midnapore district Left Front.