An international military exercise involving 13,000 troops from 16 countries kicked off in Estonia on May 2.
The exercise, dubbed Siil (Hedgehog), is scheduled to last until May 14 and is the largest such drill to be held in the Baltic country since it regained independence from the Soviet Union in 1991.
Part of the exercise will be held in neighboring Latvia.
Besides the Estonian military, some 2,000 troops from 15 countries -- the United States, Britain, Germany, France, Canada, Poland, Ukraine, Finland, Sweden, Denmark, Belgium, Ireland, Latvia, Lithuania, and Georgia -- were set to take part.
In addition to the regular military, Estonian reservists, police, and rescue services are also attending the exercise, which will focus on territorial defense and will be held in three separate stages.
Estonia and Latvia border Russia and together with the third Baltic state, Lithuania, were part of the Soviet Union after being annexed by Moscow during World War II.
The three, which are now members of NATO and the European Union, have voiced concerns about Moscow's intentions in the region, especially since Russia's seizure and annexation of Ukraine's Crimean Peninsula in March 2014.