Sweden's armed forces said Wednesday they were following a Russian submarine that entered the Baltic Sea a day earlier, amid mounting tensions in the region.

"A Russian submarine entered the Baltic Sea yesterday via the Great Belt," a Danish strait, the Swedish military said in a statement .

"The armed forces' jet fighters and warships met up with the submarine in the Kattegatt (strait between Denmark and Sweden) and are now following it," it said.

The Swedish navy, which released two images of the incident, said it was "a routine operation taking place in close collaboration with our allies," adding that it had a "good overview of our immediate vicinity."

Sweden's armed forces said Wednesday they were following a Russian submarine that entered the Baltic Sea a day earlier, calling

See Full Page