Latvia started a previously unannounced military exercise in the south-east of the EU country on the border with Belarus over the weekend.
Defense Minister Artis Pabriks said on Latvian television on Sunday that around 3,000 soldiers from the regular armed forces and volunteer armies of the Baltic EU and NATO countries will take part.
According to a spokeswoman for the Defense Ministry in Riga, the maneuver, which will run until December 12, is intended to train large-scale cooperation between various military units and command structures as well as logistics and mobility.
The member states of the Organization for Security and Co-operation in Europe (OSCE) - including Russia and Belarus - have been informed about the exercise, she told the Leta agency.
The situation on the EU's eastern external border has deteriorated dramatically since last week.
Furthermore, thousands of migrants on the Belarusian side on the border with Poland are waiting in makeshift camps in the forest at temperatures around freezing point.
In the past few days, groups have repeatedly tried to break through the barrier and illegally cross the border.
tfb / dpa