NATO countries are in the middle of Arctic military drills, vowing on Tuesday to defend their newest member, Finland, which is hosting its first joint NATO exercise since becoming the 31st member of the Western alliance in April.

The addition of Finland doubles the length of the border NATO shares with Russia, which launched a large-scale invasion of another neighbor, Ukraine, in February last year.

Nearly 1,000 allied forces from the United States, Britain and Norway, and also from neighboring Sweden, joined some 6,500 Finnish troops and some 1,000 vehicles for the Northern Forest exercise, Finland's biggest modern-time land force drill above the Arctic Circle.