Voting is under way in Crimea on a referendum to break away from Ukraine and become a part of Russia.
The vote comes one day after Russia vetoed a U.N. Security Council resolution urging countries not to recognize the results of the referendum, which is widely expected to be to join Russia.
Russia was the only member to vote against the measure Saturday. Thirteen other members voted for it while China abstained, saying the resolution would lead to confrontation and complications.
The resolution would have affirmed Ukrainian sovereignty by declaring that the referendum has "no validity."
China's abstention could mean more isolation of Moscow for its support of the Crimean referendum.
U.S. Ambassador Samantha Power called the resolution's defeat "a sad and remarkable moment."
Russian Ambassador Vitaly Churkin said the resolution ran counter to the principles of international law.
Crimea is a primarily ethnic-Russian majority region of Ukraine. Moscow says it has the right to protect its interests in Crimea.
Ukraine's Foreign Ministry said Saturday Russian forces have seized the village of Strilkove, near the Crimean border.
There are no reports of shots being fired, but the Ministry calls the takeover an "invasion" and demands the Russian soldiers leave.
Ukrainian border guards say the Russians are guarding a gas pumping station in the town.
Elsewhere, supporters and opponents of Russian actions in Crimea rallied Saturday.
A large pro-Russian demonstration turned violent in the eastern city of Donetsk. Some protesters pushed their way past police and kicked in the glass windows and doors of the Ukrainian Security Service Building. The protesters stormed the building where they caused further damage.
Hundreds marched in Kyiv demanding Crimea remain part of Ukraine, while in Moscow, thousands of supporters of the referendum waved Russian and Soviet flags as they marched to Moscow's Revolution Square.
Opponents held a separate rally waving Ukrainian flags. Some said they fear Russian intervention in Crimea could lead to war.