Sweden, which has stayed out of military alliances since the Napoleonic Wars, applied for NATO membership together with Finland in a historic move last month. NATO's existing 30 members are set to discuss the issue this month. Turkey has threatened to hold up the applications over the two countries' perceived support for terrorist groups.
Finland and Sweden have sought security assurances from the U.S. and other NATO countries during the application period.
Kicking off the BALTOPS exercises last weekend in Stockholm, U.S. Gen. Mark Milley, chairman of the Joint Chiefs of Staff, said it was important for the NATO allies "to show solidarity with both Finland and Sweden."
Their membership in the alliance would leave Russia in a difficult military position, with the Baltic Sea encircled by NATO members except for in Russia's Baltic exclave of Kaliningrad and the Russian city of St. Petersburg and its surrounding areas.
The strategic importance of Gotland, a popular summer vacation spot for Swedes, is often viewed in relation to the Baltic countries of Estonia, Latvia and Lithuania, which are particularly worried about any Russian aggression following the Ukraine invasion. Gotland is about 100 kilometers (60 miles) from mainland Sweden and 160 kilometers (100 miles) from the coast of Latvia,
"The thing is, from here, you make supplying and supporting the Baltic states a lot easier or a lot more difficult, depending on who is in control of the island," Mikael Norrby, an Uppsala University academic, told The Associated Press.
Coinciding with the NATO exercises, Russia's Baltic Fleet launched its own military exercises this week. The fleet's press service referred to the maneuvers Tuesday as a scheduled exercise focused on "various types of security tasks," including the tracking and destruction of enemy submarines.