'Foreign activity' in Swedish waters?
19 October 2014 Last updated at 08:31 BST
Sweden has boosted its military presence in the Stockholm Archipelago, amid rising tension between Russia and Scandinavian countries over the Ukraine crisis.
Authorities say the mobilisation of ships, troops and helicopters is in order to scour the capital's waters for "foreign underwater activity", while media reports suggest Sweden is searching for a submarine.
Tim Allman reports