Submarines will commence underwater exercises around the Western Isles for ten days from the early hours of Monday.
Some 55 warships and submarines, 70 aircraft and around 13,000 personnel from 13 countries are taking part in Exercise Joint Warrior which runs until Friday 24 April.
Nato warships and small high speed boats may accompany the submarine activity around Hebridean waters.
Local fishing boats may be “challenged” or asked to indicate their identity by military ships. They also face been buzzed by helicopters.
Minesweepers will be hunting for mock ordnances in Broadbay, laid on the bottom and also floating above the seabed, between Back and Point.
Dutch, Turkish, Polish, German and Norwegian vessels will join Royal Navy ships during the manoeuvres.
Military aircraft will also be flying on aerial exercises.
The Nato war games are designed to improve joint operations between the participating armed forces.
Warships on manoeuvres around the Western Isles
8 April 2015