The manoeuvres are part of what the Russian strongman sees as the fortification of a new front line with NATO Among the units deployed to the area are armoured vehicles, tanks and fighter jets.
Navy Captain Danny Hernandez told the Washington Free Beacon that the exercises were being closely monitored.
He said: We are extremely concerned about the increasing tensions near the administrative boundary between Crimea and the rest of Ukraine.
We urge both sides to avoid provocative steps or rhetoric that could escalate the situation.
Officials told the publication similar movements were seen before Vladimir Putin carried out his deceptive annexation of the Crimea.
Such manoeuvres have reduced the warning time available to the US if he decides to launch another attack.
In June it was reported Russia was constructing an army base near the border which it considers to be a new front line with NATO.
A Reuters reporter who visited the Russian town of Klintsy, about 30 miles from Ukraine, saw a makeshift army camp, large numbers of newly-arrived servicemen and military vehicles.
Reuters
Russian armoured personnel carriers travel through the Crimea during its 2014 annexation from Ukraine
Getty Images
New army manoeuvres in the area have sparked fears of another military engagement
Two soldiers in camouflage gear who were manning a checkpoint in a forest turned the reporter away, saying they were guarding a special military site.
Over the past 12 months, Russia has continued carrying out military manoeuvres in the area while NATO carries out exercises in its eastern flank.
Confrontational rhetoric from both sides has also intensified to levels not seen since the Cold War.
Poster Comment:
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The leaders of both Russia and Ukraine gain more job security when they are rattling their sabers. The people of both countries do not want war. Job security.