KIEV: Russia executed a de facto military takeover of a strategic region in Ukraine as the parliament in Moscow gave President Vladimir Putin a green light Saturday to proceed to protect Russian interests.

The newly installed government in Kiev was powerless to react to the swift takeover of Crimea by Russian troops already in Ukraine and more flown in, aided by pro-Russian Ukrainian groups.

Putin's move follows President Barack Obama's warning Friday ''there will be costs'' if Russia intervenes militarily, sharply raising the stakes in the conflict over Ukraine's future and evoking memories of Cold War brinkmanship.

The explicit reference to the use of troops escalated days of conflict between the two countries, which started when Ukraine's pro-Russian president was pushed out by a protest movement of people who wanted closer ties to Europe.

''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 in his request sent to parliament.

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 upper house also recommended that Moscow recalls its ambassador from Washington over Obama's comments.

Ukraine had already accused Russia on Friday of a ''military invasion and occupation'' of the Crimea peninsula, where Russia's Black Sea fleet is based.

Ukrainian Prime Minister Arseny Yatsenyuk called on Moscow ''to recall their forces, and to return them to their stations,'' according to the Interfax news agency.

''Russian partners, stop provoking civil and military resistance in Ukraine.''

The crisis was sparked when Ukraine's deposed president, Victor Yanukovych, ditched a deal for closer ties to the European Union and instead turned toward Moscow.

Months of protests followed, culminating in security forces killing dozens of protesters and Yanukovych fleeing to Russia.

Ignoring Obama's warning, Putin said the ''extraordinary situation in Ukraine'' was putting at risk the lives of Russian citizens and military personnel stationed at a naval base that Moscow has maintained in the Black Sea peninsula since the Soviet collapse.

Reflecting a degree of caution, Deputy Foreign Minister Grigory Karasin who presented Putin's request to the upper house, told reporters that the motion doesn't mean that the president would immediately send additional troops to Ukraine.

''There is no talk about it yet,'' he said. Putin's spokesman, Dmitry Peskov, also said in remarks carried by RIA Novosti news agency that the president hadn't yet made a decision to use the Russian military in Ukraine.

He added that Putin hasn't yet made a decision on recalling the ambassador either.

The UN Security Council called an urged meeting on Ukraine Saturday, and the European Union foreign ministers will hold an emergency meeting Monday to discuss the crisis.

Putin's 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 areas in eastern and southern Ukraine, where many oppose the new authorities in Kiev.

Pro-Russian protests were reported in the eastern cities of Kharkiv, Donetsk and Luhansk and the southern port of Odessa.

Ukraine's population is divided in loyalties between Russia and Europe, with much of western Ukraine advocating closer ties with the European Union while eastern and southern regions look to Russia for support. Crimea, a semi-autonomous region of Ukraine, is mainly Russian-speaking.

In Saturday's parliamentary session in Moscow, a deputy house speaker said Obama had insulted Russia and crossed a ''red line,'' and the upper house recommended the Russian ambassador in Washington be recalled. It will be up to Putin to decide whether that happens.

In Crimea, the pro-Russian prime minister who took office after gunmen seized the regional Parliament 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.

Ukraine's acting president, Oleksandr Turchynov, said the election of Sergei Aksyonov as prime minister of Crimea was invalid.

Ukrainian officials and some Western diplomats said that a Russian military intervention is already well underway after heavily armed gunmen in unmarked military uniforms seized control of local government buildings, airports and other strategic facilities in Crimea in recent days.

Crimea only became part of Ukraine in 1954 when Soviet leader Nikita Khrushchev transferred jurisdiction from Russia, a move that was a mere formality when both Ukraine and Russia were part of the Soviet Union. The Soviet breakup in 1991 meant Crimea landed in an independent Ukraine.