Chinook helicopters were seen thundering along the east coast of Tayside and Fife on Sunday.
The aircraft are thought to be taking part in a military training exercise based at Leuchars Station.
It is understood the army base is being used during Exercise Chameleon, which is mainly being hosted by RAF Leeming.
Around 1pm a Chinook was spotted travelling over the Tay towards Dundee and on to Angus.
A helicopter was also spotted flying over Fife.
There were reports elsewhere of paratroopers jumping out of an aircraft near Arbroath.
A source said helicopters arrived at Leuchars on Sunday and were expected to stay at the base until September 17.
