STORY: Servicemen prepared to repel possible threats from Belarus and to deter offensive actions from the state border.
The joint drills included servicemen driving military armoured vehicles and taking positions with weapons in the forest.
The drills took place the same day Russian President Vladimir Putin proclaimed Russia's annexation of a swathe of Ukraine in a pomp-filled Kremlin ceremony, promising Moscow would triumph in its "special military operation" against Kyiv even as some of his troops faced potential defeat.
Russia moved to annex these regions after holding what it called referendums – votes that were denounced by Kyiv and Western governments as illegal and coercive.
Putin's proclamation of Russian rule over 15% of Ukraine - the biggest annexation in Europe since World War Two - has been firmly rejected by Western countries and even many of Russia's close allies.
Ukrainian President Volodymyr Zelenskiy, speaking in Kyiv after Putin, said he was ready for peace talks if and when Russia got a new president and announced that Ukraine was formally applying for fast-track membership of the NATO military alliance.