Reuters reports Sweden's military is working on two new observations that could be evidence of suspected "foreign underwater activity" near the country's capital, a senior naval officer said on Tuesday. Swedish forces have been scouring the sea off Stockholm since Friday, after what the military called three credible reports of activity by foreign submarines or divers using an underwater vehicle. The vessels were unidentified, but Swedish during the 1980s the Swedish navy from time to time hunted suspected Soviet submarines in its waters. In recent months, Swedish jets have been scrambled to meet Russian planes crossing into the country's air space, a pattern repeated in the Baltics where NATO has responded. Finland has complained that Russia has violated its air space and that the Russian navy interfered with the operations of a state environmental research vessel in international waters in August and September.