MOSCOW (Reuters) - Russia rolled out air defense systems built to operate in sub-zero Arctic conditions on Tuesday as it showcased its military might at a parade on Moscow's Red Square.

The parade, an annual event commemorating the Soviet Union's victory over Nazi Germany in World War Two, took place under gray skies as President Vladimir Putin looked on from a platform alongside Soviet war veterans.

The Kremlin has been flexing its military muscle in the hydrocarbon-rich Arctic region, as it vies for dominance with rivals Canada, the United States and Norway.

"Lessons of the past war remind us to be vigilant, and the Armed Forces of Russia are capable of repelling any potential aggression," Putin told the parade.

"But for an effective battle with terrorism, extremism, neo-Nazism and other threats the whole international community needs to be consolidated. ... We are open for such cooperation."

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An aerial show by Russia's air force, including warplanes that have flown missions to support Syrian President Bashar al-Assad's army, was canceled because of low visibility.

Smaller parades were held in cities across Russia, in Ukraine's Crimea Peninsula, which Russia annexed three years ago, as well as at Russia's Hmeimim air base in Syria.

Moldovan President Igor Dodon was the only foreign dignitary to attend the Moscow parade. In prior years, leaders including German Chancellor Angela Merkel and Chinese President Xi Jinping had attended.

Tuesday's parade was the first time Russia had showcased its Tor-M and Pantsir SA air defense systems, painted in the white and black colors of the country's Arctic forces.

Also on display were columns of troops, tanks and Russia's Yars intercontinental ballistic missile system.

Putin said: "The Russian soldier today, as in all times, showing courage and heroism, is ready for any feat, for any sacrifice for the sake of his motherland and people."

(Reporting by Dmitry Solovyov, Alexander Winning and Denis Dyomkin; editing by Ralph Boulton)