Russian President Vladimir Putin has received a standing ovation in parliament after defending Crimea's breakaway vote to join Moscow.
To regular applause during a televised address to the nation, he pointed out that 82% of Crimea's residents turned out for Sunday's referendum, and more than 96% of them voted to join Russia.
He said the vote was "quite convincing" and was held "in full accordance with democratic procedures and international legal norms".
"The (Crimean) issue has a vital importance, a historic importance for all of us" he said.
Mr. Putin said he did not want to "carve up" Ukraine, but said the West had "crossed a line" with its behaviour over the former Soviet country.
"They are trying to drive us into a corner," he told a joint session of parliament in Moscow.
His speech came as he signed a treaty making Crimea officially part of Russia, and coincided with a mass rally, celebrating ties between Russia and Crimea, in Red Square.
Mr. Putin also thanked Ukraine's soldiers for "not staining themselves in blood in Crimea".
He said the peninsula's future was decided without a shot being fired because it was "practically impossible to fight the will of people".
Western leaders say Crimea's vote was illegal and have refused to recognise its decision to join Russia.
The EU and US have imposed travel bans and asset freezes on senior Moscow officials, and British Prime Minister David Cameron said "there will be further consequences" if Russia takes further action to destabilise Ukraine.
US Vice President Joe Biden has arrived in Poland on a trip designed to show US resolve against Russia's actions. His two-day mission in Eastern Europe is aimed at reassuring allies that Washington understands their anxieties about Ukraine and will protect them if needed.
Meanwhile, one of Ukraine's top politicians says his country is ready to fight if Russian soldiers cross the border from Crimea into mainland Ukraine.
Serhiy Taruta, governor of the eastern city of Donetsk, warned "We're going to have a war. Our people will take up arms and they will protect our country".
Under the Russian treaty, Crimea will ditch Ukraine's currency, the Hryvnia, and adopt the Rouble next month. It is also due to move time zones adopting Moscow time - which is two hours ahead of Kiev - on March 30th.
The peninsula is also offering Crimean soldiers the chance to join the Russian army.
Minister for European Affairs Paschal Donohoe told Newstalk Breakfast earlier he attended the committee yesterday at which sanctions were announced.
He says the diplomatic route is the priority for now.
Read Vladimir Putin's Executive Order recognising the Republic of Crimea
