Swedish Navy hunting for foreign submarines in the Stockholm archipelago

It seems Cold War is returning - Sweden's military is investigating reports of 'foreign underwater activity' in the Stockholm archipelago dailymail.co.uk. They are using high-tech-equipped naval vessels, aircraft and home guard forces.

As revealed by Chief of operations Jonas Wikstrom, there is some information 'from a credible source' that set in motion the hunt for the submarine. The investigation is believed to be a part of a wider intelligence operation.
Wikstrom has not divulged much but has only sad that the purpose of the exercise was to find out whether 'there had been or still is ongoing foreign underwater activity' by using ships, planes and Territorial Army personnel.
Sweden is neutral and its armed forces have ruled out that it could be some sort of natural phenomenon. Observers see this as reminiscent of the Cold War, when Sweden's armed forces routinely hunted for Soviet submarines in its waters.

Incidentally, the search for the submarine comes in the wake of last month's aerial interception of Russian planes by UK jets when Royal Air Force jets were deployed from Scotland to intercept Russian military 'Bear' aircraft that appeared to be flying too close to the airspace it guards.
Aircraft based at RAF Lossiemouth, based in Moray, were sent to identify the aircraft that turned out to be Tu-95 Russian Bear H bombers and they were spotted in international airspace.