U.S. and British troops have carried out the first large-scale NATO defensive drill on the border between Poland and Lithuania, rehearsing for a possible scenario in which Russia might try to sever the Baltic states from the rest of the Western alliance.

The frontier runs for 104 km (65 miles) through farmland, woods and low hills, in an area known as the Suwalki Gap. If seized by Russia, it would cut off Estonia, Latvia and Lithuania.

Over two days, U.S. helicopters and British aircraft took part in exercises that also involved troops from Poland, Lithuania and Croatia in a simulated defense of the potential flashpoint.

“The gap is vulnerable because of the geography. It’s not inevitable that there’s going to be an attack, of course, but … if that was closed, then you have three allies that are north that are potentially isolated from the rest of the alliance”, U.S. Lieutenant General Ben Hodges told Reuters.

Russia denies any plans to invade the Baltics, and says it is NATO that is threatening stability in Eastern Europe by building up its military presence there and staging such war games.

Read the whole story from Reuters.