Russia may be heightening tension with Sweden after the country's submarines are suspected of traveling into waters in the Stockholm Archipelago, the latest act of military provocation between Russian and Western countries.
This week, Sweden's military deployed planes and ships after being alerted to "foreign underwater activity" off Stockholm.
Swedish military officials said information about the incursion came from a "credible source" and that the incident is under careful investigation.
"We have support for the analysis work we are now carrying out in the area in the form of ships, planes and territorial army personnel. The area is heavily trafficked, which is why it's important for us to go public with information about what we're doing," said Jonas Wikström, commanding officer of the operation.
Officials did not provide specifics about the incident or name the country that made the threat, but Russia is strongly suspected.
Swedish news outlet The Local noted,
In recent months, Sweden has seen an uptick in Baltic Sea manoeuvres by the Russian air force -- including an incident in September when two SU24 fighter-bombers allegedly entered Swedish airspace in what then Foreign Minister Carl Bildt called "the most serious aerial incursion by the Russians" in almost a decade.
American officials have warned about the capabilities of Russian submarines. Navy Vice Adm. Michael Connor said that Russia remains capable of striking American military bases with its fleet of nuclear-armed submarines.
"The Soviet Union devolved into Russia but they kept their nuclear capabilities," Connor said. "They are now re-growing those capabilities and others. As they re-grow, we find that modern Russia appears to have some aspirations both territory-wise and influence-wise that are reminiscent of the way they behaved when we had the Soviet Union."
Russia has also been blamed for a number of other acts of military provocation, including a separate incident in which airplanes flew so close to the borders of the United States and Canada that both nations were forced to scramble jets to chase away the Russian planes.