The Russian parliament has approved President Vladimir Putin's request to use the Russian military in Ukraine's Crimea region, further raising tensions between the neighbors.
Saturday's vote made official what Ukrainian authorities have described as an ongoing deployment of Russian troops in Crimea.
At a meeting of the interim government in Kyiv Saturday, Ukraine's acting defense minister said 6,000 additional Russian troops have been deployed on Ukrainian soil.
Ukraine's newly-appointed Prime Minister Arseny Yatsenyuk demanded Russia stop what he called its "provocations" in Crimea and said the Ukrainian military in the majority Russian area is on high alert..
The Black Sea peninsula, part of Ukraine since the Soviet Union collapsed in 1991, is now the focus of turmoil in Ukraine after pro-Russian President Viktor Yanukovych was ousted a week ago.
The newly-appointed pro-Russian prime minister of Crimea, Sergei Aksyonov, claimed control of the region's military and other security forces Saturday and appealed to Russian President Vladimir Putin for help restoring "peace and calm."
Russia's lower house of parliament also urged Mr. Putin Saturday to take steps to stabilize the situation in Crimea. But U.S. President Barack Obama warned Russia Friday not to intervene in Ukraine, saying there would be consequences.
Russia, meanwhile, has said its troop movements in Crimea, where it leases a naval base in Sevastopol, fall within agreements with Ukraine
Ukraine has refused to recognize the Crimean prime minister, with acting Ukrainian President Oleksandr Turchynov issuing a statement declaring Mr. Aksyonov's appointment a violation of Ukraine's constitution.
Mr. Aksyonov was appointed by the Crimean parliament earlier this week as tensions soared over Crimea's resistance to the new authorities in Kyiv, who took power last week.
VOA correspondent Elizabeth Arrott says unidentified soldiers and military vehicles have appeared in the Crimean region, well beyond their local base. She said at least a dozen were stationed outside parliament in the Crimean capital of Simferopol Saturday. She said she also saw gunmen in camouflage at the Simferopol airport Friday.
There are also reports of Russian troops surrounding the state-run television station in Simferopol.
The head of Russia's upper house of parliament said Saturday she could not rule out the possibility that a limited contingent of troops could be sent to Crimea to assure the security of the Black Sea fleet in Sevastopol and Russian citizens living in the region.
Crimea, placed under Ukrainian control in 1943 by late Soviet leader Nikita Khrushchev, has a tiny border with Russia on its far eastern point. Most of the people living in Crimea are ethnic Russians, but the region is also home to ethnic Muslim Tartars who generally show disdain toward Russia.
Ukrainian President Turchynov, said Friday Russian actions in Crimea are "naked aggression." He likened the actions to events that led up to Russia's 2008 invasion of Abkhazia - a pro-Russian region of Georgia.
In another development Saturday, Russia's Energy Ministry has threatened not to continue Ukraine's gas price discount because of Ukraine's unpaid balance. Gazprom said Saturday Ukraine's outstanding gas debt for 2013 and this year is $1.55 billion.