This was announced by Gen. Philip Breedlove Tuesday, Censor.NET reports citing CBS.
Breedlove said that Russian forces "capable of being nuclear" are being moved to the Crimean Peninsula, but NATO doesn't know if nuclear weapons are actually in place.
Breedlove also told news agencies at a NATO base near Naples that about eight Russian battalion task groups have been sighted along the border between Ukraine and Russia Russian-backed separatists have been fighting Ukrainian soldiers in eastern Ukraine despite a cease-fire proclaimed weeks ago.
Read also: Russia Is Preparing Full-Scale Invasion into Ukraine - Ukraine's Permanent Representative to UN
Last week, Breedlove said Russia was discussing plans to put aircraft in Crimea, which Moscow annexed from Ukraine earlier this year.
NATO has reported a spike in Russian military flights over the Black, Baltic and North seas and the Atlantic Ocean, with groups of Russian warplanes conducting large-scale maneuvers in international airspace.