http://www.nytimes.com/2014/08/23/world/europe/russia-moves-artillery-units-into-ukraine-nato-says.html?_r=0

WASHINGTON — The Russian military has moved artillery units manned by Russian personnel inside Ukrainian territory in recent days and was using them to fire at Ukrainian forces, NATO officials said on Friday.

The West has long accused Russia of supporting the separatist forces in eastern Ukraine, but this is the first time it has said it had evidence that the Russian military was operating in Ukrainian territory.
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