(FOX NEWS) -- Ukraine's acting president announced that he has put the country's armed forces on high alert after the Russian parliament unanimously voted to grant President Vladimir Putin permission to mobilize the country's military in Ukraine.
Oleksandr Turchynov said Saturday he had also ordered increased security at nuclear power plants, airports and other strategic infrastructure, because of the threat of "potential aggression."
The Russian parliament unanimously voted Saturday to grant President Vladimir Putin permission to mobilize the country's military in Ukraine and asked that the country's ambassador in Washington be recalled after earlier statements by President Obama.
Putin said that the mobilization is needed to protect ethnic Russians and the personnel of a Russian military base in Ukraine's strategic region of Crimea. But the request came a day after Obama warned Moscow that "there will be costs" if it intervenes militarily in Ukraine.
"I'm submitting a request for using the armed forces of the Russian Federation on the territory of Ukraine pending the normalization of the socio-political situation in that country," Putin said before the vote.
Putin's call came as pro-Russian demonstrations broke out in Ukraine's Russian-speaking east, where protesters raised Russian flags and beat up supporters of the new Ukrainian government.
Russia's move sharply raised the stakes in the conflict following the ouster of Ukraine's pro-Russian president last week by a protest movement aimed at turning Ukraine toward the European Union and away from Russia. Ukraine has accused Russia of a "military invasion and occupation" -- a claim that brought an alarming new dimension to the crisis, and raised fears that Moscow is moving to intervene on the strategic peninsula where Russia's Black Sea fleet is based.
The move also appears to formalize what Ukrainian officials described as an ongoing deployment of Russian troops in the strategic region of Crimea. His motion loosely refers to the "territory of Ukraine" rather than specifically to Crimea, raising the possibility that Moscow could use military force in other Russian-speaking provinces in eastern and southern Ukraine where many oppose the new authorities in Kiev.
In Crimea, the pro-Russian regional prime minister had earlier claimed control of the military and police there and asked Putin for help in keeping peace, sharpening the discord between the two neighboring Slavic countries.
Sergei Aksenov, the head of the main pro-Russia party on the peninsula, said in a statement reported by local and Russian news agencies that he appealed to Russian President Vladimir Putin "for assistance in guaranteeing peace and calmness on the territory of the autonomous republic of Crimea."
Aksenov declared that the armed forces, the police, the national security service and border guards will answer only to his orders. He said any commanders who don't agree should leave their posts.
Russia's Foreign Ministry, meanwhile, said unidentified gunmen sent by Kiev had attempted overnight to seize the Crimea region's Interior Ministry offices and that people had been wounded in the "treacherous provocation," Reuters reported.
Ukrainian border guard vessels were put on combat alert in the Crimea region on Saturday and were leaving port to prevent the capture of military bases and ships, Interfax news agency quoted the border guard service as saying, according to Reuters.
Russian troops moved into Crimea Friday, U.S. officials told Fox News, prompting Ukraine to accuse Russia of an "armed invasion."
Ukraine's defense minister said on Saturday Russia had "recently'' brought 6,000 additional personnel into Ukraine and that the Ukrainian military were on high alert in the Crimea region, Reuters reported.
Ukraine's Prime Minister Arseny Yatsenyuk opened a cabinet meeting by calling on Russia not to provoke discord in Crimea.
"We call on the government and authorities of Russia to recall their forces, and to return them to their stations," Yatsenyuk was quoted as saying by the Interfax news agency. "Russian partners, stop provoking civil and military resistance in Ukraine."
At the White House, President Obama said the U.S. government is "deeply concerned" by reports of Russian "military movements" and warned any violation of Ukraine's sovereignty would be "deeply destabilizing."
U.S. officials told Fox News they see "evidence of air and maritime movement into and out of Crimea by Russian forces" although the Pentagon declined to officially "characterize" the movement.
Earlier Friday, Agence France Press quoted a top Ukranian official as saying Russian aircraft carrying nearly 2,000 suspected troops have landed at a military air base near the regional capital of the restive Crimean peninsula.
A spokesman for the Ukrainian border service said eight Russian transport planes have landed in Crimea with unknown cargo.
Serhiy Astakhov told The Associated Press that the Il-76 planes arrived unexpectedly Friday and were given permission to land, one after the other, at Gvardeiskoye air base, north of the regional capital, Simferopol.
Astakhov said the people in the planes refused to identify themselves and waved off customs officials, saying they didn't require their services.
Earlier in the day, Russian armored vehicles rumbled across Crimea and reports surfaced of troops being deployed at airports and a coast guard base – signs of a more heavy-handed approach to the crisis from Moscow.
The Associated Press and Reuters contributed to this report.