A delegation headed by the commander of Russia's ground forces, Oleg Salyukov, visited Belarus on Thursday to inspect the combat readiness of a joint force stationed there, the Belarusian defense ministry said.
The visit took place a day after Salyukov was named as one of the deputy commanders of Russia's military operation in Ukraine in the latest of a series of reshuffles.
Russia and its close ally Belarus have beefed up their joint military grouping in Belarus and plan to hold joint aviation drills there from next Monday.
Ukraine is concerned Russia will invade via the Belarus-Ukraine border
The exercises form part of a pattern of activity that has prompted Ukraine to warn that Russian President Vladimir Putin may try to use Belarus to launch a new ground invasion of Ukraine from the north.
Belarusian leader Alexander Lukashenko allowed Putin to use his country as one of the launchpads to invade Ukraine last February when Russian forces were beaten back in an attempt to take the capital Kyiv.
Military analysts say Russia has also used Belarusian facilities to train up newly mobilized soldiers who were called up last September to boost its forces in Ukraine.
However, Belarus has not sent its own troops into Ukraine in support of Russia's "special military operation" there.