Russian and Belarusian fighter jets have conducted a joint border patrol, the Belarusian defense ministry said on Wednesday.
It did not mention exactly what areas the flight covered. Russia and Belarus - which have a formal union - border several European Union states including Poland and also share a border with Ukraine which says Russia may be planning to invade it after amassing tens of thousands of troops nearby.
Moscow denies having such plans, but says Ukraine's aspirations to join NATO are a threat to Russia's national security.