MOSCOW -- In a gilded Kremlin hall used by czars, Vladimir Putin redrew Russia's borders Tuesday by declaring the Crimean Peninsula part of the motherland -- provoking a surge of emotion among Russians who lament the loss of empire and denunciations from Western leaders who called Putin a threat to the world.

In an ominous sign, a Ukrainian serviceman and a member of a local self-defence brigade were killed by gunfire in Crimea just hours after Putin's speech, the first fatalities stemming from the Russian takeover.

While Putin's action was hailed by jubilant crowds in Moscow and cities across Russia, Ukraine's new government called the Russian president a threat to the "civilized world and international security," and the U.S. and Europe threatened tougher sanctions against Moscow.

Vice-President Joe Biden, meeting with anxious European leaders in Poland, denounced what he called "nothing more than a land grab."

"The world has seen through Russia's actions and has rejected the flawed logic," Biden said.

In an emotional 40-minute speech televised live from the Kremlin's chandeliered St. George hall, Putin said the time has come to correct a historical injustice and stand up to Western pressure by incorporating Crimea.

"In people's hearts and minds, Crimea has always been an integral part of Russia," he declared.

He dismissed Western criticism of Sunday's Crimean referendum -- in which residents of the strategic Black Sea peninsula voted overwhelmingly to break off from Ukraine and join Russia -- as a manifestation of the West's double standards.

"They tell us that we are violating the norms of international law. First of all, it's good that they at least remember that international law exists," Putin said, pointing at what he called the U.S. trampling of international norms in wars in Serbia, Iraq, Afghanistan and Libya.

"Our Western partners led by the United States prefer to proceed not from international law, but the law of might in their practical policies," he said.

Often interrupted by raucous applause, Putin said the rights of ethnic Russians in Ukraine had been abused by the new Ukrainian government and insisted Crimea's vote to join Russia was legitimate and reflected its right for self-determination.

Denouncing what he called Western arrogance, hypocrisy and pressure, Putin warned that the West must drop its stubborn refusal to take Russian concerns into account. He pointed at NATO's eastward expansion, the alliance's U.S.-led missile defence plans and, finally, the Western moves to pull Ukraine into its orbit.

"If you push a spring too hard, at some point it will spring back," he said. "You always need to remember this."

Only hours after Putin boasted that the Russian takeover of Crimea was conducted without a single shot, a Ukrainian military spokesman said a Ukrainian serviceman was killed and another injured when a military facility in Crimea was stormed Tuesday by armed men.

A Crimea police spokeswoman, Olga Kondrashova, later was quoted by Interfax news agency as saying that a Ukrainian serviceman and a member of a local self-defence brigade were killed by gunfire coming from the same location, and two other people were wounded.

Ukrainian Prime Minister Arseniy Yatsenyuk declared the violence showed the conflict "has gone from the political stage to the military by the fault of the Russians."

Thousands of Russian troops had overtaken Crimea two weeks before Sunday's hastily called referendum, seizing some Ukrainian military bases, blockading others and pressuring Ukrainian soldiers to surrender their arms and leave. Putin insisted the Russian troops were in Crimea under a treaty with Ukraine that allows Russia to have up to 25,000 troops at its Black Sea fleet base in Crimea.

The West and Ukraine described the Crimean referendum as illegitimate and being held at gunpoint.

Crimea had been part of Russia since the 18th century until Soviet leader Nikita Khrushchev transferred it to Ukraine in 1954, a mere formality until the 1991 Soviet breakup left the region part of Ukraine. Putin noted that both Russians and Crimea's majority ethnic Russian population see annexation as correcting a historic insult.

"It was only when Crimea suddenly ended up in a different country that Russia realized that it had not simply been robbed but plundered, Putin said.

"Millions of Russians went to bed in one country and woke up in another, overnight becoming ethnic minorities in former Soviet republics, while the Russian nation became one of the biggest, if not the biggest, ethnic group in the world to be divided by borders."

Despite the massing of thousands of Russian troops on Ukraine's eastern border, Putin insisted his nation had no intention of invading other regions in Ukraine.

"We don't want a division of Ukraine. We don't need that," he said.

Ukraine's political turmoil has become Europe's most severe security crisis since the Balkan wars of the early 1990s, and what NATO does about Ukraine is crucial.

"If Ukraine goes to NATO or the EU, Putin will do everything so that it goes there without the east and south," said Vadim Karasyov, a Kyiv-based political analyst.

"Putin basically told the West that Russia has the right to veto the way Ukraine will develop. And if not, then Crimea is only a precedent of how pieces of Ukraine can be chopped off, one by one."

Putin insisted the months of protests in the Ukrainian capital, Kyiv, which prompted President Viktor Yanukovych to flee to Russia, had been instigated by the West to weaken Russia. He cast the new Ukrainian government as illegitimate, driven by radical "nationalists, neo-Nazis, Russophobes and anti-Semites."

Ukraine's new government called Putin dangerous.

"Today's statement by Putin showed in high relief what a real threat Russia is for the civilized world and international security," Ukrainian Foreign Ministry spokesman Evhen Perebinis said on Twitter. Annexation of Crimea "has nothing to do with law or with democracy or sensible thinking."

For his part, Putin accused the West of cheating Russia and ignoring its interests in the years that followed the Soviet collapse.

"They have constantly tried to drive us into a corner for our independent stance," Putin told the gathered lawmakers and top officials. "But there are limits. And in the case of Ukraine, our Western partners have crossed a line. They have behaved rudely, irresponsibly and unprofessionally."

Insisting that Crimea's vote was valid, Putin pointed to Kosovo's independence bid from Serbia -- a move supported by the West and opposed by Russia -- and said Crimea's secession repeated Ukraine's own secession from the Soviet Union in 1991.

"I have heard residents of Crimea say that back in 1991 they were handed over like a sack of potatoes," Putin said. "What about Russia? It lowered its head and accepted the situation, swallowing the insult. Our country was going through such hard times then that it simply was incapable of defending its interests."

Following the speech, Putin and Crimean officials signed a treaty for the region to join Russia. While it must still be endorsed by Russia's constitutional Court and ratified by both houses of parliament, Valentina Matviyenko, the speaker of the upper house, said those steps could be completed by the end of the week.

Late Tuesday, Putin attended a rally on Red Square where tens of thousands gathered to support Crimea joining Russia. "Putin said it -- Putin did it!" one banner read.

In Donetsk, the centre of Ukraine's eastern Donbass coal-mining region, 37-year-old businessman Aleksei Gavrilov hailed Crimea joining Russia and said Donbass also historically belonged to Russia.

"Ukraine is just a made-up, fake project that was created to destroy Russia," he said. "Everything Putin said is perfectly correct, and I support him completely."

Igor Nosenko, a bar manager watching Putin's speech in Kyiv, said he felt like he was "in some kind of surrealist world where a person is saying that white is black."

"It can be dangerous for the whole world, since it is absolutely unclear what this person has in his head," he said of Putin.

With limited options, the U.S. and European Union sought ways to show they would not stand idly by. A day after freezing assets and imposing other sanctions against Russian officials and Ukrainian supporters, the Group of Eight world powers suspended Russia's participation. The elite club, now the Group of Seven, are to meet next week in Europe to discuss further action.

"It is completely unacceptable for Russia to use force to change borders, on the basis of a sham referendum held at the barrel of a Russian gun," British Prime Minister David Cameron said. "The choice remains for President Putin: Take the path of de-escalation or face increasing isolation and tighter sanctions."