Sweden takes another step towards NATO with a joint war game, aiming to work together in the event of an armed conflict in the future.
Neutral Sweden has launched its biggest war games in two decades with support from NATO countries, drilling 19,000 troops after years of spending cuts that have left the country fearful of Russia's growing military strength.
On the eve of Russia's biggest manoeuvres since 2013, which NATO says will be greater than the 13,000 troops Moscow says are involved, Sweden will simulate an attack from the east on the Baltic island of Gotland, near the Swedish mainland.
Sweden, like the Baltics, Poland and much of the West, has been troubled by Russia's 2014 annexation of Ukraine's Black Sea peninsula Crimea and its support for pro-Russian separatists in eastern Ukraine.
Around 1,500 troops from the United States, France, Norway and other NATO allies are taking part in the exercise dubbed Aurora.
Non-NATO member Sweden has decided to beef up its military after having let spending drop from over 2 percent of economic output in the early 1990s to around 1 percent, and is re-introducing conscription.
The armed forces, which at one point could mobilise more than 600,000, stand at just 20,000, with 22,000 more Home Guard volunteers.
NATO generals say the Aurora exercise is not a response to Russian exercises that start on Thursday.
But Byden, speaking as US and French forces displayed mobile surface-to-air missile systems to be deployed during the exercise, stressed the importance of NATO for Sweden.
The government is determined to stick to the country's formal neutrality. But like its non-NATO neighbour Finland, Sweden has been drawing closer to NATO, allowing closer cooperation with alliance troops, with a view to working together in the event of an armed conflict.