Russian President Vladimir Putin flew in to Crimea on Friday, marking the Soviet victory in World War Two and proclaiming the success of the peninsula since its accession to Russia.

In east Ukraine, where anti-government activists plan a referendum on Sunday to follow Crimea’s accession to Russia, several people were reported killed in the port of Mariupol, one of the bloodiest clashes yet between Ukrainian forces and the eastern opposition.

The head of NATO, locked in its gravest confrontation with Russia since the Cold War, condemned Putin’s visit to Crimea, whose split from Ukraine has not been recognized by Western powers. He also renewed doubts over an assurance by the Kremlin leader that he had pulled back troops from the Ukrainian border.

The government in Kiev called Putin’s visit, his first since the takeover of the region two months ago, a “provocation” that was intended deliberately to escalate the crisis.

Watching a military parade in Sevastopol on the Black Sea, Putin said: “I am sure that 2014 will go into the annals of our whole country as the year when the nations living here firmly decided to be together with Russia, affirming fidelity to the historical truth and the memory of our ancestors.

“Much work lies ahead but we will overcome all difficulties because we are together, which means we have become stronger.”

Earlier in the day, he had presided over the biggest Victory Day parade in Moscow for years. The passing tanks, aircraft and intercontinental ballistic missiles were a reminder to the world – and Russian voters – of Putin’s determination to revive Moscow’s global power, 23 years after the Soviet collapse. “The iron will of the Soviet people, their fearlessness and stamina saved Europe from slavery,” Putin said in a speech to the military and war veterans gathered on Red Square.

But NATO Secretary-General Anders Fogh Rasmussen said: “His visit to Crimea is inappropriate.” The head of the U.S.-led defense pact was speaking in formerly Soviet Estonia, one of a host of east European nations that joined after the collapse of communism, seeking refuge from the power of Moscow.

Report compiled with information from Reuters.