About a thousand Russian soldiers will participate in a military exercise in Belarus in the coming days.
The exercises will run from Tuesday to Friday and will be held during a troubled period when Belarusian President Aleksandr Lukashenko is under pressure.
In Belarus, the results of the recent presidential elections have been protested for weeks, with protesters and opposition saying Lukashenko has committed fraud.
Russia is the president’s main ally.
Last week, NATO held a military exercise in Lithuania, a neighbour of Belarus. Lukashenko then saw this as a serious military threat to his country.
On Monday, opposition leader Svetlana Tichanovskaya will speak with ministers from all EU countries about the situation in Belarus.