BERGEN , Sweden, May 4 (UPI) -- Naval forces of 10 NATO countries and Sweden gathered in Norway Monday to begin an annual submarine-hunting exercise, this year with increased relevance.
Although the drills are confined to the North Sea, the nearby Baltic Sea has been the site this year of reports of unidentified and foreign vessels in territorial waters. A craft believed to be a submarine was spotted off Finland's coast last week, and a mystery vessel was spotted near Sweden last year; most observers believe the vessels originated in Russia.