The military exercise was launched just days ahead of major Russian maneuvers with Belarus, code named Zapad 2017, which are scheduled to take place between September 14 and 20 around the Baltic Sea, western Russia, Belarus and the Russian exclave of Kaliningrad. Some members of the alliance, including the Baltic States and Poland have questioned Moscow's real intentions and said the number of troops involved could be much higher than official figures.
The exercise in Ukraine comes as Russia is gearing up for its major military exercise, Zapad 2017, which is expected to involve tens of thousands of troops operating along NATO's borders in Western Russia, the Russian European enclave of Kaliningrad and Belarus.
In a statement announcing the start of the exercises Russia's defense ministry insisted the maneuvers are "of a strictly defensive nature and are not directed against any other state or group of countries".
North Atlantic Treaty Organisation has also bolstered its presence in its easternmost member states that were dominated by Moscow during the Cold War and remain concerned about the Kremlin's intentions in the region.
The exercises will last until September 20.
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But for North Atlantic Treaty Organisation allies, especially jittery members such as Poland and the Baltic States which only broke free from Moscow's grip 25 years ago, such reassurances have not dampened suspicion.
Kiev and the West have accused Russian Federation of buttressing the rebels and sending in regular troops across the border, claims Moscow has repeatedly denied.
"We urge Russian Federation to share information regarding its exercises and operations in NATO's vicinity to clearly convey its intentions and minimize any misunderstandings", Pentagon spokesman US Army Lt. Col. Michelle Baldanza told CNN. "We see a more aggressive Russian Federation, we have to deal with that".
The Kremlin has vigorously defended its right to hold exercises and has long blamed the United States for ratcheting up tensions by expanding North Atlantic Treaty Organisation up to its borders and holding its own provocative drills.