The head of NATO on Friday urged Russia to "step back from the brink" and described President Vladimir Putin's visit to recently annexed Crimea as inappropriate.

During a visit to Estonia Secretary-General Anders Fogh Rasmussen also said there's no "visible evidence" of Russian claims of a troop withdrawal from the border with Ukraine.

"We've seen such announcements also in the past, without any withdrawal of Russian troops so we're very cautious," the Dane told reporters.

"I would be the first to welcome it if Russian troops were pulled out, if we see a clear and meaningful withdrawal, because it would contribute to de-escalate the crisis."

Asked about Putin's first visit to Crimea since the region became part of Russia, Fogh Rasmussen noted that NATO doesn't recognize the annexation.

"We still consider Crimea as Ukrainian territory and from my knowledge the Ukrainian authorities haven't invited Putin to visit Crimea so from that point of view his visit to Crimea is inappropriate," he said.

In his speech, the NATO chief accused Russia of destabilizing the security situation in Europe.

"My first message is to Russia. Step back from the brink," he said. He also reassured Estonia and Baltic neighbors Latvia and Lithuania that as NATO members they can count on the alliance's "rock solid" commitment to defend them.