Nato has released satellite images that it says show Russian combat troops and "sophisticated heavy weaponry" inside Ukraine.
The images were taken in late August and reportedly show "self-propelled artillery" moving in convoy and establishing firing positions near the city of Krasnodon in eastern Ukraine.
In a statement, Nato said the images provide "concrete examples of Russian activity inside Ukraine" but represent "only the tip of the iceberg in terms of the overall scope of Russian troop and weapons movements".
Nato also said other images show Russian forces transferring weapons and other military hardware to separatist forces, and "substantial activity" on the Russian side of the border with Ukraine.
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