Russia on Thursday kicked off a week of war games with its ally Belarus that have the United States and NATO neighbours watching anxiously, as Moscow seeks to cement possible political fissures in the Kremlin's own orbit.
Russia's defence ministry said the war games dubbed 'Zapad 2017', or 'West', had begun, and elements of its First Tank Army had been ''put on alert'' and moved into Belarus for the exercise. Airborne units stationed in Russia also were mobilised and prepared to join the drills, the ministry said.
Russia denied charges that the exercises were being conducted with a lack of transparency, and accused the West of ''whipping up hysteria''.
The exercises will last until 20 September. They are being conducted on military ranges in Belarus, western Russia, the Russian exclave of Kaliningrad, and in the Baltic Sea.
''We reject complaints of these exercises not being transparent,'' Kremlin spokesman Dmitry Peskov said on a conference call with reporters. ''We believe that whipping up hysteria around these exercises is a provocation.
''It is a normal practice for any country to hold such exercises. Everything is being held in line with international law.''
Russian President Vladimir Putin may visit one of the stages of these drills, he said.
At a time of renewed Cold War-style tension between Russia and the North Atlantic Treaty Organisation (NATO), the symbolism was striking, according to The Washington Post. The Soviet-led Warsaw Pact once used the Zapad exercises to prepare for potential war with the West. The job of the Soviet tanks was to smash through NATO lines, including the 300,000 US troops once stationed in Europe.
The US force in Europe is down to 30,000 now, and many countries that once formed the Soviet bloc have since become members of NATO.
But Russia sees itself hemmed in by a hostile, expanding force, and Russian President Vladimir Putin has vowed to prevent revolutions in the former Soviet region similar to the 2014 rebellion that established a pro-Western government in Ukraine.
The scenario Russian and Belarusan forces are playing out involve a ''Western coalition'' of imaginary states: Lubenia, Vesbaria and Veishnoria, in which Russian and Western observers see similarities to NATO members Poland, Lithuania and Latvia. In the war game scenario, the three enemies are attempting to change the regime in Belarus's capital, Minsk; turn Belarus against Russia; and annex parts of Belarus to Veishnoria.
The first phase of the drills pits Russian and Belarusan forces against ''illegal armed formations'' and ''saboteur groups'' of the Western coalition that have infiltrated Belarus.
The Russian announcement that the games had begun was accompanied by the reassurance - repeated by Moscow for weeks - that the exercise is ''of an entirely defensive nature and is not aimed at any other states.''
Concerns in the Western alliance were raised by the apparent difference between official Russian figures about the size of the exercise - 12,700 troops, 138 tanks, 40 jets and helicopters - and Western estimates, based on troop and equipment movements, that the number could range from 70,000 to as many as 100,000 participants.
In a statement, the Pentagon said that while Russia and Belarus had taken some steps towards providing transparency, there were concerns about the official estimate of troop numbers.
''We urge Russia to share information regarding its exercises and operations in NATO's vicinity to clearly convey its intentions and minimise any misunderstandings,'' Lieutenant Colonel Michelle Baldanza, a Pentagon spokeswoman, said in a statement.
''In response to this uncertainty, the US has built a joint, persistent rotational presence of air, land, and sea presence in the region to support our Allies,'' she added.
Western military officials have expressed concern that Zapad 2017 will serve as a ''Trojan horse,'' allowing Moscow to leave behind some of the military personnel and equipment it deployed for the drills.
The last time Russia held a Zapad drill, in 2013, it used some of the forces involved to capture the Crimean Peninsula from Ukraine the next year.
Senior officials in the Baltics last week said they saw the games as a rehearsal of the capability to seal off Lithuania, Latvia and Estonia and to deny access to the Baltic Sea to NATO forces attempting to come to their rescue. They also see a larger strategic goal: to demonstrate to US and NATO leaders the high cost of defending the Baltics and thus bringing into question the viability of the alliance.
NATO, which conducted its own exercises involving 25,000 service members from 20 nations in Europe this summer, has stationed four battalions - including US troops - in the Baltic states and Poland. Ukraine, locked in a conflict with Russia-backed separatists, is conducting its own military exercises, called ''Unflinching Tenacity,'' and neutral Sweden has begun exercises with NATO that involve 19,000 troops.
In Minsk, Col Vladimir Makarov, a Belarusan military spokesman, said that all 3,000 Russian military personnel in the country would leave when the war games conclude on Wednesday.
But critics of President Alexander Lukashenko, whose rule since 1994 once earned Belarus the nickname ''Europe's last dictatorship,'' remain suspicious.
''This is a threat to us, because they are dragging Belarus into this hybrid war, they are on our land practicing fighting a war with NATO, and we don't need that,'' said Nikolai Statkevich, a leader of protests against the exercises in Minsk last weekend. A former presidential candidate, Statkevich served a number of years in prison after being detained in 2011.