President Vladimir Putin has led parades in Moscow's Red Square - to mark the ex-Soviet Union's defeat of Nazi Germany - and then in Crimea. NATO says Putin's visit to the annexed Ukrainian peninsula was "inappropriate."
Russia's military marked the 1945 Soviet victory over Nazi Germany on Friday, with a ceremony in Moscow attended by ex-Soviet-era veterans and presided over by President Putin.
Putin later reviewed Russia naval forces in Crimea, the Black Sea peninsula annexed by Moscow in March after a controversial referendum to secede from Ukraine.
The massive display in Crimea's port city of Sevastapol, home to Russia's Black Sea fleet, included multiple fly-overs by Russian military aircraft, prompting a terse response from the interim authorities in Kyiv.
"Such a provocation is yet another confirmation that Russia is deliberately pursuing further escalation of tensions in Ukrainian-Russian relations," Ukraine's foreign ministry said in a statement.
The pro-Western interim government in Ukraine had cancelled most of its May 9 parades. Former Soviet countries mark the end of the Second World War a day later than those in western Europe, with the official 1945 ceasefire timed so that it would straddle midnight on May 8 and 9 across the time zones.
Visiting Estonia's capital, Tallinn, NATO Secretary General Anders Fogh Rasmussen described Putin's visit to Crimea as "inappropriate."
Rasmussen said NATO had no visible confirmation of the withdrawal of Russian troops from Ukraine's border.
During his televised Red Square address in Moscow, Putin said May 9 remained Russia's "most important holiday" and told surviving Soviet veterans "we are proud of you."
The parade - backdropped by the crisis over Ukraine - featured 11,000 soldiers, 150 military vehicles and a fly-over of 70 Russian military aircraft, accompanied by martial music and patriotic songs.
On Thursday, Russia had showcased its missiles by test-firing three nuclear-capable multi-stage rockets.
The Russian defense ministry said a Topol M missile was launched in northern Russia while two submarines fired a rocket each into training grounds.
Putin visit to Normandy
Despite Western sanctions and condemnation of Russia's annexation in March of the southern Ukrainian peninsula of Crimea, it emerged on Thursday that Putin was likely to be welcomed to Normandy, France, next month.
It would amount to the first direct encounters between Putin and Western leaders, including US President Barack Obama, since the outbreak of the Ukraine crisis.
The June 6 commemoration will mark the 70th anniversary of the US-led Allied D-Day landings in France in 1944 that opened a western front against occupying Nazi forces while Soviet troops advanced on Nazi Germany from the east.
Chancellor Merkel said she "hoped that despite the different opinions and the great conflict we have right now, a joint remembrance of a difficult time - of World War II - is possible."
French President Francois Hollande said that while he had differences with Putin, he had not forgotten the millions of Russian lives that were lost in the war.
French Defense Minister Jean-Yves Le Drian went further, telling the channel BFM that cancelling Putin's invitation would be a historical insult.
"It is in the order of things that (Putin) should be there," Le Drian said, adding that the Allied invasion begun in Normandy would not have been successful "without the Eastern front."
"In these moments of commemoration it is important that all those who took part should be present," Le Drian said.
French officials began inviting world leaders to Normandy months ago, well before Russia's annexation of Crimea and stationing of 40,000 troops on Ukraine's border.
Leaders of the Group of Seven (G7) industrialized nations will gather without Russia in Brussels before heading to Normandy.
(Reuters, DW, dpa)