KIEV, Ukraine — Russia's military staged a provocative new act of aggression Saturday, occupying a natural gas distribution center and village on a strip of Ukrainian land near Crimea and prompting Kiev's Ministry of Foreign Affairs to denounce "a military invasion by Russia."
The incident marked the first face-to-face standoff between the Ukrainian and Russian militaries outside the Crimean peninsula, suggesting that Moscow is testing the will of Kiev amid fears of further Russian incursions in eastern and southern Ukraine, which, like Crimea, has a large number of ethnic Russians.
The move came ahead of today's vote in Crimea on whether its residents want to break away from Ukraine and join Russia.
Russia on Saturday blocked passage of a U.N. Security Council resolution that would have declared that today's referendum "can have no validity, and cannot form the basis for any alteration of the status of Crimea." The veto was expected, but in a possible sign of Russian isolation, Moscow's close ally China opted to abstain rather than join Moscow in vetoing the measure.
The referendum will be held under the eyes of Russian troops, who effectively took control of Crimea late last month after protesters overthrew the pro-Moscow Ukrainian government.
On Saturday, Russian troops in four helicopter gunships and three armored combat vehicles descended on the natural gas facility near the village of Strilkove about 1:30 p.m. local time, according to Ukrainian officials. The Russians said they had seized the site out of fears it would be targeted by terrorists, according to a Ukrainian Defense Ministry official who spoke to the Washington Post on the condition of anonymity.
In a statement, Ukraine's Foreign Ministry demanded that the Russian side withdraw immediately and said that "Ukraine reserves the right to use all necessary measures to stop the military invasion by Russia."
In Washington, President Barack Obama's national security advisers gathered at the White House on Saturday afternoon to discuss the Ukraine crisis, and officials said Obama was being regularly updated.
Earlier in the day, Ukrainian officials reported a shootout between pro-Russian and pro-Ukrainian demonstrators that took place overnight in the eastern Ukrainian city of Kharkiv.
Two people were dead and several injured after a group of Russian separatists approached offices being used by pro-Ukrainian activists, according to Tatiana Gruzinskaya, spokeswoman for the city's mayor.
In Moscow, tens of thousands of antiwar demonstrators turned out to protest Russia's intervention in Ukraine, marking the largest political rally in the Russian capital in more than a year.