Story highlights Ukraine is mobilizing troops around the country, official says 
 
 U.S. Secretary of State John Kerry condemns Russia's "invasion and occupation'' 
 
 Putin says Russia reserves the right to defend its interests and people 
 
 Obama made clear violating Ukraine's sovereignty would impact Russia's standing 
 
 Leaders of a shaky new government in Ukraine were mobilizing troops Sunday amid signs of Russian military intervention in Ukraine's Crimean peninsula. 
 
 The Ukrainian National Security Council ordered the mobilization as Russian President Vladimir Putin appeared to dismiss warnings from world leaders to avoid military intervention in Crimea, a senior Ukrainian official, Andriy Parubiy, said. The news came as evidence mounted that pro-Russian forces were already in Crimea, an autonomous region of eastern Ukraine with strong loyalty to neighboring Russia. 
 
 A sense of escalating crisis swirled Saturday night, with U.S. Secretary of State John Kerry condemning what he called "the Russian Federation's invasion and occupation of Ukrainian territory" despite a statement by Russian Prime Minister Dmitry Medvedev that no decision had been made on whether Moscow would dispatch forces. 
 
 Russia has not confirmed it deployed thousands of troops to the region following reports that armed, Russian-speaking forces wearing military uniforms -- without insignia -- patrolled key infrastructure sites. 
 
 It was the latest in fast-moving developments that saw Russia's Parliament sign off on Putin's request to send military forces into Ukraine, raising the stakes in the escalating game of brinksmanship. 
 
 Putin cited in his request a threat posed to the lives of Russian citizens and military personnel based in southern Crimea. Ukrainian officials have vehemently denied Putin's claim. CNN crews in and around Crimea's regional capital of Simferopol, meanwhile, have not seen evidence of a Ukrainian military presence. 
 
 Putin's move prompted world diplomats to call for a de-escalation of tensions that have put the two neighbors on a possible path to war and roiled relations between Russia and the United States. 
 
 In what appeared to be an illustration of the growing schism between the two world powers, U.S. President Barack Obama and Putin spoke for 90 minutes -- with each expressing their concern over the mounting crisis, according to separate statements released by their respective governments. 
 
 According to the Kremlin, Putin told Obama that Russia reserves the right to defend its interests in the Crimea region and the Russian-speaking people who live there. 
 
 "President Obama made clear that Russia's continued violation of Ukraine's sovereignty and territorial integrity would negatively impact Russia's standing in the international community," according to a statement released by the White House. 
 
 Lean to the West, or to Russia? 
 
 Ukraine, a nation of 45 million people sandwiched between Europe and Russia's southwestern border, has been plunged into chaos since the ouster a week ago of President Viktor Yanukovych following bloody street protests that left dozens dead and hundreds wounded. 
 
 Ukraine has faced a deepening schism, with those in the west generally supporting the interim government and its European Union tilt, while many in the east preferring a Ukraine where Russia casts a long shadow. 
 
 Nowhere is that feeling more intense than in Crimea, the last big bastion of opposition to the new political leadership. Ukraine suspects Russia of fomenting tension in the autonomous region that might escalate into a bid for separation by its Russian majority. 
 
 Ukraine acting President Oleksandr Turchynov took to the airwaves late Saturday to warn that any Russian military intervention would lead to war. Prime Minister Arseniy Yatsenyuk said his country was ready to mobilize its forces to protect strategic locations, including nuclear power plants. 
 
 'The troops are already there' 
 
 The crisis raised alarm bells with the worlds diplomats, with Ukrainian ambassador Yuriy Sergeyev calling on member nations of the U.N. Security Council to take a stand against what he called Russia's "clear act of aggression.'' 
 
 "... The troops are already there, and their number is increasing every hour," Sergeyev said during an emergency meeting of the Security Council. 
 
 Russia now has 15,000 troops in Ukraine's Crimea region, Yegor Pyvovarov, the spokesman for the Ukraine mission at the United Nations, told CNN ahead of Saturday's session of the Security Council. He did not say how Ukraine arrived at that number, or whether that included troops already stationed at a Russian base in the region. 
 
 Vitaly Churkin, Russia's ambassador to the United Nations, rejected Ukraine's calls to stop Russian intervention. "We can't agree with this at all," he said. 
 
 He blamed members of the European Union for causing the bloody street demonstrations in Ukraine. 
 
 "It's a difficult situation in the past few hours," Churkin said, claiming that there were Ukrainian forces from Kiev en route to to overthrow the local pro-Russian governments in eastern Ukraine and Crimea and establish new ones that would enforce the power of the new Ukrainian government. 
 
 Churkin has said reports of Russian troops taking charge of positions on the ground were rumors and noted that rumors "are always not true." 
 
 Crimea's pro-Russian leader asked for help 
 
 The Russian Parliament vote Saturday came on the day that the newly installed pro-Russian leader of Crimea, Sergey Aksyonov, asked Putin for help in maintaining peace on the Black Sea peninsula -- where Russia's fleet is based at Sevastopol. 
 
 Security forces "are unable to efficiently control the situation in the republic," he said in comments broadcast on Russian state channel Russia 24. Aksyonov was installed as the region's premier after armed men took over the Crimean Parliament building on Thursday. 
 
 Aksyonov said that a referendum on greater Crimean autonomy, originally set for May 25, would be moved to March 30. 
 
 Yatsenyuk called the Russian presence in Crimea a provocation. 
 
 "Ukraine will not be provoked, we will not use force. We demand that the government of the Russian Federation immediately withdraw its troops and return to their home bases," he said during a televised Cabinet meeting. 
 
 Meanwhile, Ukraine Defense Minister Igor Tenyukh said his nation's military was at its highest state of military readiness. He credited negotiations during the day between the Ukrainian and Russian naval chiefs with easing tensions and said more negotiations were planned for Sunday. 
 
 Airspace in the region reopened Saturday, a day after Ukraine accused Russian Black Sea forces of trying to seize two airports in Crimea but said Ukrainian security forces had prevented them from taking control. 
 
 Groups of armed men, dressed in uniforms without identifying insignia, patrolled the airports in Simferopol and the nearby port city of Sevastopol. The men remained at the airports Saturday, but Yevgey Plaksin, director of the airport in Simferopol, said airport services were working. 
 
 Obama: Warning to Russia 
 
 Meanwhile, Obama's message to Russia also reached Congress, where the ranking member of the Senate Armed Services Committee called for an immediate response to Russia's move. 
 
 "Every moment that the United States and our allies fail to respond sends the signal to President Putin that he can be even more ambitious and aggressive in his military intervention in Ukraine," Sen. John McCain, R-Arizona, said in a statement. 
 
 He called on Obama to "make clear what costs Russia will face for its aggression and to impose those consequences without further delay." 
 
 Senior White House officials say they are looking at a wide range of possible economic and diplomatic measures to present to Obama that would show Putin there is a cost to his actions in Ukraine. 
 
 The White House has already announced the United States will suspend participation in preparatory meetings for the G-8 Summit that will bring world leaders together in June in Sochi, Russia. 
 
 "Going forward, Russia's continued violation of international law will lead to greater political and economic isolation," according to a statement released by the administration. 
 
 Pressure was mounting on Russia as leaders from the EU and the UK joined an international outcry, with EU High Representative Catherine Ashton deploring Russia's "unwarranted escalation of tensions." 
 
 During a telephone call with Putin, U.N. Secretary General Ban Ki-Moon said he told the Russian leader that it was crucial to "restore calm and proceed to an immediate de-escalation of the situation." 
 
 "Cool heads must prevail and dialogue must be the only tool in ending this crisis," he said. ||||| MOSCOW/KIEV Russian President Vladimir Putin demanded and won his parliament's approval on Saturday to invade Ukraine, where the new government warned of war, put its troops on high alert and appealed to NATO for help. 
 
 Putin's open assertion of the right to send troops to a country of 46 million people on the ramparts of central Europe creates the biggest confrontation between Russia and the West since the Cold War. 
 
 Prime Minister Arseny Yatseniuk, leading a government that took power after Moscow's ally Viktor Yanukovich fled a week ago, said Russian military action "would be the beginning of war and the end of any relations between Ukraine and Russia". 
 
 Acting President Oleksander Turchinov ordered troops to be placed on high combat alert. Foreign Minister Andriy Deshchytsya said he had met European and U.S. officials and sent a request to NATO to "examine all possibilities to protect the territorial integrity and sovereignty of Ukraine". 
 
 Putin's move was a direct rebuff to Western leaders who had repeatedly urged Russia not to intervene, including U.S. President Barack Obama, who just a day before had held a televised address to warn Moscow of "costs" if it acted. 
 
 Troops with no insignia on their uniforms but clearly Russian - some in vehicles with Russian number plates - have already seized Crimea, an isolated peninsula in the Black Sea where Moscow has a large military presence in the headquarters of its Black Sea Fleet. Kiev's new authorities have been powerless to stop them. 
 
 The Russian forces solidified their control of Crimea and unrest spread to other parts of Ukraine on Saturday. Pro-Russian demonstrators clashed, sometimes violently, with supporters of Ukraine's new authorities and raised the Russian flag over government buildings in several cities. 
 
 "This is probably the most dangerous situation in Europe since the Soviet invasion of Czechoslovakia in 1968," said a Western official on condition of anonymity. "Realistically, we have to assume the Crimea is in Russian hands. The challenge now is to deter Russia from taking over the Russian-speaking east of Ukraine." 
 
 Putin asked parliament to approve force "in connection with the extraordinary situation in Ukraine, the threat to the lives of citizens of the Russian Federation, our compatriots" and to protect the Black Sea Fleet in Crimea. 
 
 The upper house swiftly delivered a unanimous "yes" vote, shown live on television. 
 
 Western capitals scrambled for a response, but it was limited to words. A U.S. official said Defense Secretary Chuck Hagel had spoken to his Russian counterpart Sergei Shoigu. The official said there had been no change in U.S. military posture. 
 
 EU foreign affairs chief Catherine Ashton urged Moscow not to send troops. Swedish Foreign Minister Carl Bildt said this would be "clearly against international law". Czech President Milos Zeman likened the crisis to the 1968 invasion of Czechoslovakia. 
 
 "Urgent need for de-escalation in Crimea," tweeted NATO Secretary-General Anders Fogh Rasmussen. "NATO allies continue to coordinate closely." 
 
 Putin said his request for authorization to use force in Ukraine would last "until the normalization of the socio-political situation in that country". His justification - the need to protect Russian citizens - was the same as he used to launch a 2008 invasion of Georgia, where Russian forces seized two breakaway regions and recognized them as independent. 
 
 FLAGS TORN DOWN 
 
 So far there has been no sign of Russian military action in Ukraine outside Crimea, the only part of the country with a Russian ethnic majority, which has often voiced separatist aims. 
 
 A potentially bigger risk would be conflict spreading to the rest of Ukraine, where the sides could not be easily kept apart. 
 
 As tension built on Saturday, demonstrations occasionally turned violent in eastern cities, where most people, though ethnically Ukrainian, are Russian speakers and many support Moscow and Yanukovich. 
 
 Demonstrators flew Russian flags on government buildings in the cities of Kharkiv, Donetsk, Odessa and Dnipropetrovsk. 
 
 In Kharkiv, scores of people were wounded in clashes when thousands of pro-Russian activists stormed the regional government headquarters, and fought pitched battles with a smaller number of supporters of Ukraine's new authorities. 
 
 Pro-Russian demonstrators wielded axe handles and chains against those defending the building with plastic shields. 
 
 In Donetsk, Yanukovich's home region, lawmakers declared they were seeking a referendum on the region's status. 
 
 "We do not recognize the authorities in Kiev, they are not legitimate," protest leader Pavel Guberev thundered from a podium in Donetsk. 
 
 Thousands of followers, holding a giant Russian flag and chanting "Russia, Russia" marched to the government headquarters and replaced the Ukrainian flag with Russia's. 
 
 Coal miner Gennady Pavlov said he backed Putin's declaration of the right to intervene. "It is time to put an end to this lawlessness. Russians are our brothers. I support the forces." 
 
 "WAR HAS ARRIVED" 
 
 On Kiev's central Independence Square, where protesters camped out for months against Yanukovich, a World War Two film about Crimea was being shown on a giant screen, when Yuri Lutsenko, a former interior minister, interrupted it to announce Putin's decree. "War has arrived," Lutsenko said. 
 
 Hundreds of Ukrainians descended on the square chanting "Glory to the heroes. Death to the occupiers." 
 
 Although there was little doubt that the troops without insignia that have already seized Crimea are Russian, the Kremlin has not yet openly confirmed it. It described Saturday's authorization as a threat for future action rather than confirmation that its soldiers are already involved. 
 
 A Kremlin spokesman said Putin had not yet decided to use force, and still hoped to avoid further escalation. 
 
 In Crimea itself, the arrival of troops was cheered by the Russian majority. In the coastal town of Balaclava, where Russian-speaking troops in armored vehicles with black Russian number plates had encircled a small garrison of Ukrainian border guards, families posed for pictures with the soldiers. A wedding party honked its car horns. 
 
 "I want to live with Russia. I want to join Russia," said Alla Batura, a petite 71-year-old pensioner who has lived in Sevastopol for 50 years. "They are good lads...They are protecting us, so we feel safe." 
 
 But not everyone was reassured. Inna, 21, a clerk in a nearby shop who came out to stare at the APCs, said: "I am in shock. I don't understand what the hell this is... People say they came here to protect us. Who knows? ... All of our (Ukrainian) military are probably out at sea by now." 
 
 The rapid pace of events has rattled the new leaders of Ukraine, who took power in a nation on the verge of bankruptcy when Yanukovich fled Kiev last week after his police killed scores of anti-Russian protesters in Kiev. Ukraine's crisis began in November when Yanukovich, at Moscow's behest, abandoned a free trade pact with the EU for closer ties with Russia. 
 
 For many in Ukraine, the prospect of a military conflict chilled the blood. 
 
 "When a Slav fights another Slav, the result is devastating," said Natalia Kuharchuk, a Kiev accountant. 
 
 "God save us." 
 
 (Additional reporting by Alissa de Carbonnel in Balaclava, Ukraine, Timothy Heritage, Stephen Grey and Peter Graff in Kiev, Lina Kushch in Donetsk and Peter Apps in London; Writing by Peter Graff; Editing by Alistair Lyon) ||||| Unidentified gunmen wearing camouflage uniforms block the entrance of the Crimean Parliament building in Simferopol, Ukraine, Saturday, March 1, 2014. The discord between Russia and Ukraine sharpened... (Associated Press) 
 
 KIEV, Ukraine (AP) — Russian President Vladimir Putin has asked parliament for permission to use the country's military in Ukraine, the Kremlin said Saturday. 
 
 Putin said the move is needed to protect ethnic Russians and the personnel of a Russian military base in Ukraine's strategic region of Crimea. 
 
 "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 a statement released by the Kremlin. 
 
 He sent the request to the Russian legislature's upper house, which has to approve the motion, according to the constitution. 
 
 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 Slavic neighbor countries. 
 
 It was the latest escalation 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. 
 
 Armed men described as Russian troops took control of key airports and a communications center in Crimea on Friday. 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. 
 
 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 is mainly Russian-speaking. 
 
 Crimean's prime minister, Sergei Aksyonov, declared that the armed forces, the police, the national security service and border guards in the region will answer only to his orders. 
 
 Ukrainian Prime Minister Arseny Yatsenyuk opened a Cabinet meeting in the capital, Kiev, by calling on Russia not to provoke discord in Crimea, a peninsula on the Black Sea. 
 
 "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." 
 
 ___ 
 
 Vladimir Isachenkov reported from Moscow.
– Tensions in the Ukraine just keep escalating. Although President Obama warned Russia not to send troops, Vladimir Putin today got official permission to do just that. The Russian president asked parliament to let him send forces to the "territory of Ukraine" to protect ethnic Russians in the region of Crimea and possibly elsewhere, reports AP. And in a not-so-surprising development, lawmakers agreed unanimously, reports CNN. Earlier, the pro-Russian prime minister of Crimea had made a formal request of his own for Putin's help. The Ukraine government in Kiev, meanwhile, says Russia already has sent 6,000 troops to Crimea, even if it hasn't acknowledged as much, reports the BBC. The upshot is that "the Black Sea peninsula appeared to slip beyond Kiev's control," says Reuters. And it quotes one political analyst who says "the scenario of Crimea's withdrawal (from Ukraine) has been accelerated." Soldiers presumed to be either part of the Russian military or at least backed by the military control the airports, government buildings, and the main communications center in Crimea. Airspace around the main airport in Simferopol has been shut down.