Nato war games due to start in and around Scotland
One of Europe's largest Nato military exercises starts in the UK next week.
Joint Warrior is held twice a year - in April and October - and includes several locations in Scotland and in the sea off its coast.
The first of this year's war games will involve 18 countries and feature 55 submarines and warships, including USS Anzio and USS Porter from the US.
It will also feature 70 aircraft, some from RAF Lossiemouth in Moray, and 13,000 personnel.
The Royal Navy said the exercise will see "significant naval and aerial activity off the west and east coast of Scotland, including amphibious landings on the west coast".
Joint Warrior, which runs from 11 to 24 April, will also involve periodic jamming of GPS signals.
The Royal Navy said jamming will be limited to a confined area in the north-west of Scotland.
It added: "The relevant authorities, including aviation and maritime communities, have been consulted and procedures are in place for any unforeseen activity that might arise."
Jamming during Joint Warrior in October 2011 was suspended after complaints from Western Isles fishermen.
The latest war games come just weeks after a fisherman claimed a submarine may have snagged itself on his trawler as it fished off the Western Isles, an area were elements of Joint Warrior's training are held.
Angus Macleod said he and his four crew were "extremely lucky" after his net was continually dragged in front of his 62ft boat.
The Royal Navy said there were no British or Nato submarines in the area at the time.
There has been speculation in recent months that Russian submarines have been operating off the Scottish coast.
Mr Macleod's wooden Aquarius boat was fishing for haddock, monkfish and skate about 10 miles east of the Butt of Lewis.