Warships from Russia's Black Sea Fleet took the position off Crimea's western coastline on Thursday to help strengthen the peninsula's air defences, a Crimean military source informed the RIA news agency.
Missiles will come as close as 30 kilometers to Crimean airspace.
Ukraine ratcheted up tensions with Moscow on Wednesday by warning the Kremlin its army meant to hold two days of missile-launching exercises near the border with Russian-annexed Crimea.
Russia's Foreign Ministry on November 30 called the planned missile tests a "new large-scale provocation", saying they were aimed at "escalating the conflict between Ukraine and Russian Federation".
"This zone is within Russian air traffic controllers' zone of responsibility, but this will not affect flight safety", he reportedly said.
Ukraine has vowed to uphold global laws in its upcoming drill; however, given that Crimea is considered Ukrainian under worldwide law, this does not make clear how close the exact maneuvers of the Kherson drill will be to the territory.
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Last month, a disabled man described how he was attacked in a cinema in western India for failing to stand for the anthem. The act prohibits desecration of or insult to the Constitution, national anthem , flag and the country's map.
He said the war games included air defence units as well military drones and S-300 ground-to-air missile systems.
Kyiv insists the tests of medium range surface-to-air missiles, in the southern Kherson region bordering the territory annexed by Moscow in 2014, conform to worldwide law.it says the aim of the tests is to bolster its defence capabilities.
According to the United Nations, the conflict has claimed nearly 10,000 lives and left hundreds of thousands displaced.
The reason for the standoff is the close proximity of Kherson region to the peninsula of Crimea, which formally belongs to Ukraine but which Russian Federation has held since 2014.
"We consider such actions by the Ukrainian security bodies against Russian citizens as another flagrant provocation and demand their immediate return to Russia", a statement by the ministry's press service said.
However, Moscow is now saying that the testing exercises are affecting Russian territory too.