There are still "hundreds" of Russian troops, including special forces, in Ukraine, NATO spokesman Jay Janzen has said, according to Deutsche Welle.
He said that there had been a "significant" force withdrawal since Kyiv and pro-Russian rebels agreed a ceasefire.
"However, hundreds of Russian troops, including special forces, still remain inside Ukraine," Janzen said.
In addition, according to NATO, some 20,000 Russian soldiers were still deployed near the Ukrainian border.
