As the Russian national anthem played and parliamentarians chanted "Russia! Russia!" Russian President Vladimir Putin and Crimean leaders signed a treaty Tuesday making the peninsula part of the Russian Federation.
The annexation comes just two days after 96.8 per cent of Crimeans voted for union with Russia in a referendum criticized by the Ukrainian and Western governments as illegal.
Leaders of the G7 nations, including Canada, will meet next week to discuss the situation, the White House announced on Tuesday.
U.S. Vice-President Joe Biden denounced Russia's actions in Crimea as "nothing more than a land grab," and warned of further sanctions.
Earlier, Mr. Putin told a special session of Russia's parliament that the West had crossed a "red line" in Ukraine and put Russia in a position where it has to defend its interests.
"In the case of Ukraine, our Western partners have crossed a line, a red line. They've been unprofessional, they've been irresponsible," he said in a rare address to both houses of the Russian parliament.
"They were shortsighted. They didn't think of the consequences. Russia found itself at the stage where Russia couldn't give up. If you press the spring too hard, it will recoil."
"Russia has its national interests which you need to take into account."
Mr. Putin said Crimea has always been a part of Russia.
"Crimea has always been an important part of Russia in the hearts and minds of people," he said. He blamed Soviet leader Nikita Khrushchev for handing the region, which had been part of the Russian Empire since the 18th century, to then-Soviet Ukraine in 1954.
"What was [Khrushchev's] motive? Did he want to win over the Ukrainian nomenclature? Or did he want to shift the blame for the repressions in Ukraine in the 1930s. Let historians judge," Mr. Putin said.
"Russia was not just robbed, it was robbed in broad daylight."
Mr. Putin proceeded to slam the new authorities in Kiev, which he said "claim to be officials, they don't control the situation in their own country. We have no one to negotiate with."
However, he denied Russian troops were already in Crimea. "The Russian forces have not been in Crimea."
"Yes, we've strengthened our contingent, but we didn't increase the limit in troops. That limit is 25,000 troops."
He slammed the West for condemning Crimea's effort to join Russia after it supported Kosovo's unilateral declaration of independence from Serbia in 2008.
"The U.S. says that Kosovo is a unique case, so why do they think it's so unique?
"This is not just double standards, this is primitive and straightforward cynicism. … You can call the same thing black one day, and then same thing white the next day."
With tensions between Russia and the West at their highest point since the end of the Cold War, the address is one of the most important of Mr. Putin's long career.
Ahead of Mr. Putin's speech, the official Itar-Tass news service reported that he had "approved [a] draft agreement on Russia's accepting Republic of Crimea and on introduction of new federation members."
On Monday, Mr. Putin signed a decree recognizing Crimea as an independent state, clearing the way for union with Russia.
In Kiev, the Ukrainian government issued a statement expressing its "strong and unequivocal protest" against Russia's action. The government said the annexation of Crimea violated international law and it rejected Sunday's referendum in the territory as illegitimate.
Earlier on Tuesday, Prime Minister Arseniy Yatsenyuk issued a lengthy address to people in Eastern Ukraine which, like Crimea, has a large ethnic Russian population. In a pre-recorded message broadcast on television, Mr. Yatsenyuk promised to protect the Russian language and push for constitutional changes to give regions more power. Mr. Yatsenyuk also said Ukraine will not seek membership in the North Atlantic Treaty Organization.
The Prime Minister's message was designed to quell growing unease in some eastern regions where recent clashes between pro-Russian and pro-Ukrainian protesters have killed three people. There are fears in Kiev that Russia will use the disturbances as an excuse to send in troops.
"The signing of the so-called agreement on Crimea joining the Russian Federation and the corresponding address by the Russian president has nothing in common with law or democracy or common sense," foreign ministry spokesman Evhen Perebynis said in a statement.
"Putin's address very clearly demonstrates just how real the threat is that Russia poses to international security and international security."
With reports from Paul Waldie in Kiev and Reuters and Associated Press.
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