Sweden is on high alert, boosting its military presence in the Stockholm Archipelago as troops and helicopters scour the capital's waters for foreign underwater activity.
Reports suggest Sweden is searching for a submarine, possibly Russian, after the military said it had three credible sightings of foreign undersea activity during the past few days.
With most of the world's focus now on the Middle East and the escalating war with Islamic State, attention on Europe and the problems surrounding Russia's activities in the Ukraine have slipped from public attention.
But Russia is continuing to make itself felt in Europe, which is becoming more on edge as fears increase about another Cold War looming. Russia recently increased its military flights close to Swedish airspace, a move interpreted by Sweden and neighbouring Baltic states as an attempt to increase pressure on Stockholm and dissuade it from any notion of joining Nato.
Russia's ambitions in Europe are nothing new. Former Polish parliamentary speaker Radoslaw Sirorski has been quoted as saying Russian President Vladimir Putin proposed to Poland's then leader in 2008 they divide Ukraine between themselves.
Mr Putin is said to have made the proposal during Polish Prime Minister Donald Tusk's visit to Moscow in 2008. Before World War 2, Poland's territory included parts of today's western Ukraine, including some major cities such as Lwow, known as Lviv in Ukraine.
The interview, if correct, may further aggravate tension between Poland and Russia, which are already at odds over the Ukrainian crisis and Poland's arrest of two men suspected of spying for Moscow.
So far, the Swedish search for the submarine has turned up no evidence, but speculation is the mystery vessel is more likely to be a midget sub of the kind used by Russia's Spetsnaz (special forces) rather than a larger nuclear vessel.
Russia issued a statement denying any of its craft had violated Swedish sovereignty and suggested it could be a submarine from the Netherlands engaged in exercises in the Baltic. Dutch defence officials laughed off the suggestion, saying the Netherlands had participated in an exercise with Sweden but it ended last week.
A Nato official said the Swedes would not be dedicating so many assets to the search unless they were confident a foreign vessel was in its waters. A Russian-owned oil tanker, which had reportedly been circling near Swedish waters for days, started sailing in a northeasterly direction towards Russia on Sunday morning.
But it suddenly turned around and headed back in the direction of Sweden. The movements of the Liberian-flagged tanker may be connected to the search.
The official also noted the increase in Russian military activity in the Baltic since the Ukraine crisis flared up early this year, particularly Russian fighter jets close to Swedish air space.
Estonia, meanwhile, has increased surveillance of its territorial waters, with border guards looking for any anomalies.
Following the annexation of Crimea by Russia, and the implementation of economic sanctions from Western powers, Russia turned to China for much of its food and other supplies, effectively negating any major thrust to bring it into line.
Mr Putin continues to harbour ambitions for a larger Russia, and is perhaps even looking to the former USSR for inspiration as he eyes up his chances in former Soviet states.
It should not be forgotten the downing of Malaysian flight MH17 in rebel-held east Ukraine has still not been adequately explained to the families of those killed.
Australian Prime Minister Tony Abbott has been posturing about fronting Mr Putin on the issue, resulting in some push-back from the Russian leader.
With the United States now occupied in the Middle East, and President Barack Obama distracted with mid-term elections the Democrats are likely to lose, Russia appears to be using this time to deliberately provoke further conflict in Europe.
Without wanting to overstate the matter, swathes of the globe are already exploding into violence - but world leaders who ignore the ambitions of Mr Putin do so at their peril.
