Military officials in Belarus have sought to calm Western fears about major war games with Russia involving thousands of troops, tanks and aircraft, just hours before they are due to get under way.
The Zapad (West) 2017 manoeuvres that will be focused in Belarus have caused concern at Nato and in neighbouring countries.
Some members of the alliance, including the Baltic States and Poland, have criticised a lack of transparency and questioned Moscow's real intentions.
"We are not threatening anyone," Oleg Voinov, an adviser to the Belarusian Defence Minister, told journalists on Thursday.
"We have chosen military bases that are significantly removed from the borders with Ukraine, Poland, Lithuania and Latvia."
Russia-West relations have hit their lowest point since the Cold War following Moscow's annexation of Ukraine's Crimean Peninsula and continuing fighting between Russian-backed separatists and troops loyal to Kiev in eastern Ukraine.
Western worries about the planned manoeuvres have ranged from allegations Russia could use them to permanently deploy its forces to Belarus to fears of a surprise attack on the Baltics.
The war games are scheduled to kick off on Thursday evening.
Russia and Belarus have said that the exercises, which last until September 20, will involve 5,500 Russian and 7,200 Belarusian troops.
Russian military officials have said up to 70 aircraft and about 250 tanks, 200 artillery systems and 10 navy ships will also be involved.
Russia's Defence Ministry said on Thursday that elite parachute units in several Russian cities had been placed on alert to be deployed during the exercises.
Organisers have invented three "aggressor countries" - Veishnoriya, Lubeniya and Vesbasriya - to whose attacks the Russian and Belarusian militaries will simulate a response.
The Baltic States and Poland fear that these monikers are just poorly disguised terms for their own countries.
Nato Secretary-General Jens Stoltenberg has said the alliance will be closely monitoring the war games.
Despite assurances from Moscow, Russia's neighbours expect the drills to be much greater in scope than officially declared.
Estonian Defence Minister Juri Luik has said Moscow could deploy up to 100,000 troops.
There is also unease in Kiev, and Ukraine is currently conducting its own military exercises, called Unflinching Tenacity, scheduled to end on Friday.
The Zapad manoeuvres have been criticised by Belarusian opposition leaders, who have said that Russia could use the occasion to position a large, permanent contingent of troops in Belarus, leaving the country at the mercy of any armed confrontation involving Moscow.
The most recent Zapad exercises, which occur every few years, took place in 2013, just before Russia's 2014 annexation of Crimea.
Russia had leased a naval base in Crimea prior to its seizure, and used troops deployed there to quickly take over the Black Sea peninsula.