MOSCOW — President Vladimir Putin signed a treaty to make Crimea part of Russia, ignoring threats from the United States and Europe that he said were conspiring with radicals to prevent Russia from its rightful territory.
"In people's hearts and minds, Crimea has always been an integral part of Russia," Putin said, describing the takeover as"democratic" and "legal" and necessary to prevent encroachment against Russia.
Vice President Biden, in Poland to assure European allies of a U.S. commitment to their security, called Putin's move a "blatant violation of international law" that will be met with stronger sanctions than those that failed to prevent the "land grab."
As Russian troops drilled on the border of East Ukraine, soldiers broke into a Ukrainian military base in Crimea and killed one serviceman and captured several others.
Ukrainian Prime Minister Arseniy Yatsenyuk blamed Russia, saying the crisis "has gone from the political stage to the military by the fault of the Russians."
Putin's move is largely unprecedented in recent history given that international law holds generally that a people cannot secede from their nation in a referendum not approved by that country's government.
The Civil War of the United States was fought over that principle, and though Scotland may soon hold a referendum to break from England, the vote was approved by London.
Putin justified his move by saying Western powers agreed to back the secession of Kosovo from Serbia, but unlike Ukraine, which voted on a constitution that Crimeans participated in, Kosovo had been forced into a union with Serbia.
In a 40-minute speech televised from the Kremlin's white-and-gold St. George's Hall, Putin said he was righting a wrong by accepting the results of the Crimea referendum Sunday that called for annexation by Russia.
During the run-up to the referendum, which opponents boycotted, Putin maintained he had nothing to do with a drive by pro-Russian Crimeans to separate from Ukraine. On Tuesday he described the annexation purely in terms of what was best for Russia, saying he would annex Crimea to correct a "historical injustice."
The injustice Putin referred to was Ukraine's declaration of independence in 1991 from the Communist dictatorship that was the Soviet Union, now modern Russia. Crimea had been made part of Ukraine in the 1950s by the Soviets.
"Something that we thought was incredible became reality. The (Soviet Union) broke down. The events were so quick most citizens could not realize the traumatic effects of what was happening," he said.
Russia "will of course be facing foreign confrontation" Putin said, referring to threats from the West of financial sanctions. "But we have to decide for ourselves, are we to protect our national interest or just carry on giving them away forever?"
The United States has imposed economic sanctions and travel restrictions on seven Russian officials, including close aides to Putin, and four Ukrainian officials including deposed president Viktor Yanukovych, who was forced out by a vote of the Ukraine parliament after 80 people were shot to death during protests in the capital of Kiev. The European Union has taken similar measures.
Putin said the protests had been instigated by the West to weaken Russia, and described the new, interim Ukrainian government that emerged as illegitimate, driven by radical "nationalists, neo-Nazis, Russophobes and anti-Semites."
"We couldn't leave the Crimeans, otherwise it would have been treason," he said in the speech, during which the assembled lawmakers gave him several standing ovations.
Putin also said he did not want to move into other region of Ukraine, which also have large Russian-speaking populations, saying, "we don't want division of Ukraine."
In Warsaw, Biden met with Polish Prime Minister Donald Tusk and accused Russia of a "brazen military incursion."
"Russia has offered a variety of arguments to justify what is nothing more than a land grab, including what he (Putin) said today," Biden said in Poland.
"But the world has seen through Russia's actions and has rejected the flawed logic behind those actions," he said.
Biden also planned to meet the leaders of the Baltic states of Latvia, Lithuania and Estonia, which were also formerly part of the Soviet Union.
Even as Putin spoke, Western countries sought to ratchet up the pressure on Moscow.
• In London, Prime Minister David Cameron warned of "further measures" against Russia by the international community. Cameron called for a "de-escalation" in the crisis through a return of Russian forces to base and respect for Ukraine's Constitution.
• French Foreign Minister Laurent Fabius said the leader of the G-8 had decided to suspend Russia's participation in the economic group. Russia had been scheduled to host the meeting in Sochi in southern Russia.
Putin denied accusations that Russia invaded Crimea prior to the referendum Sunday. He did not deny Russian troops had fanned out into Crimea but said they were sent in line with a treaty with Ukraine that allows Russia to have up to 25,000 troops at its Black Sea Fleet base in Crimea.
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Some 97% of voters in Crimea backed a referendum for a union between Crimea and Russia, though the referendum was run by pro-Russian Crimeans who used force to take over the Crimea parliament and several top positions in the local government and call for the vote. U.S. and Europe maintain that the vote was illegal and have refused to recognize it.
British Foreign Secretary William Hague called the referendum "a mockery of democratic practice."
"It's regrettable that President Putin chose isolation, denying Russian and Crimean citizens partnership with the international community," Hague said. "The referendum was clearly illegal according to the Ukrainian constitution. Crimea is part of Ukraine and only the Ukrainian parliament has the right to call such a referendum."
Some experts have speculated that Putin's ultimate ambition is to protect ethnic Russians across the former Soviet empire.
"Putin is prepared to keep on pushing," Fiona Hill, a Russia expert at the Brookings Institution in Washington, told the Associated Press. "I wouldn't be at all surprised if he moves into other points into eastern Ukraine."
Hjelmgaard reported from London.