MOSCOW (CNN) -- Never mind what the West thinks -- the Kremlin says Ukraine's Crimea region is now part of Russia.
A signing ceremony Tuesday between Russian President Vladimir Putin, the Prime Minister of Crimea and the mayor of the city of Sevastopol made it official, the Kremlin said in a statement.
Crimea and Sevastopol, where the Russian Black Sea fleet is based, are now part of the Russian Federation, it said.
Russia's support for Crimea's secession bid, which follows a contested referendum on Sunday, has been condemned by Ukraine's interim government in Kiev, the European Union and the United States.
Putin hailed the ballot in an address to a joint session of Parliament Tuesday, saying the nearly 97% of its residents who voted to join Russia was "an extremely convincing figure."
In an hour-long speech, he argued that the vote had been entirely legitimate and stressed the historical and cultural ties between Russia and Crimea.
"In our hearts we know Crimea has always been an inalienable part of Russia," he said.
Crimea is an autonomous region within Ukraine with a majority Russian-speaking population. It has its own parliament, but the Ukrainian government had veto power over its actions.
With political instability and demonstrations rocking Ukraine in the past several months, President Viktor Yanukovych was pushed out of office and observers charged that Russia saw its chance to annex the strategic territory. The hastily called referendum Sunday resulted in 96.7% of the region's voters saying they wanted to become part of Russia, according to the Crimean Electoral Commission.
Putin denied that Russia had been militarily involved in Crimea, despite what has been stated by authorities in the Ukraine capital and international observers. "We have not used our armed forces in Crimea," Putin said.
He also said that Russia's military forces did not enter Crimea in the current crisis, but "were already there" in accordance with previous international negotiations. He praised the 22,000 Russian troops in Crimea for avoiding bloodshed.
Russia's Black Sea fleet is based in the Crimean port city of Sevastopol but the movements of its forces within Crimea are supposed to be agreed upon with Kiev.
Tensions have been simmering in Crimea since armed men in uniforms without military insignia took control of military bases and key installations -- and they appear to have boiled over into violence Tuesday.
Vladislav Seleznyov, spokesman for Ukraine's Defense Ministry, told CNN on the phone from Crimea that at least one Ukrainian officer had been injured in an assault on a base by "armed people in masks" near the regional capital, Simferopol.
"There was shooting. There are injuries. At least one Ukrainian officer has been wounded," he said.
Seleznyov said the Ukrainian officers were unarmed and standing with their hands behind their backs. He did not have details of the weapons fired.
Duma dismisses sanctions
Putin, who was greeted by a standing ovation and whose remarks were punctuated by regular and enthusiastic applause, also accused the West of "double standards" and cynicism in its response to the crisis in Crimea, citing Kosovo, which split from Serbia, as an example of a precedent.
"It's absolutely in favor of their own interests -- black today, white tomorrow," he said.
Putin earlier formally notified his nation's parliament of Crimea's accession request and signed a draft order on the agreement, the Kremlin said.
The move comes a day after Putin signed a decree recognizing Ukraine's Crimea region as a sovereign state.
Russia's parliament is expected to vote on ratifying Crimea's accession to the Russian Federation by the end of the week.
U.S. President Barack Obama dismissed Sunday's referendum in Crimea as illegal.
"The international community will continue to stand together to oppose any violations of Ukrainian sovereignty and territorial integrity, and continued Russian military intervention in Ukraine will only deepen Russia's diplomatic isolation and exact a greater toll on the Russia economy," Obama said.
Western powers slapped sanctions on more than two dozen Russian officials and their allies in Crimea, while Ukrainian officials vowed they would never accept the territory's annexation by Russia.
But the lower house of Russia's parliament, the Duma, shrugged off the sanctions Tuesday, going so far as to draft a statement calling for all its members to be listed.
"Today we suggest that the Americans include all the members of the Duma on their sanctions list. Our principles aren't for sale and we aren't afraid of sanctions."
The speaker of Russia's upper house of parliament, Valentina Matvineko, told state-run Russia-24 TV that the process of adding a new member to the Russian Federation need not take long, ITAR-Tass reported.
"We shall be acting strictly in compliance with the law. The procedure will not take long. All can be done rather promptly," she is quoted as saying.
Russia 'choosing route of isolation'
Moscow looks set to face increasing international isolation in the days ahead.
The G7 group of industrialized nations had already suspended preparations for a planned G8 summit in the Russian city of Sochi.
Now, Obama has invited his counterparts from Canada, France, Germany, Italy, Japan, the United Kingdom, and the EU to a meeting of G7 leaders next week on the margins of a nuclear security summit in The Hague, U.S. National Security Council spokeswoman Caitlin Hayden said.
The planned meeting comes amid speculation that Russia will get kicked out of the G8 because of its actions in Crimea. The G8 comprises Russia and the G7 nations.
U.S. Vice President Joe Biden, meeting with Polish Prime Minister Donald Tusk Tuesday, accused Russia's leaders of "a brazen, brazen military incursion" and said NATO would "emerge from this crisis stronger and more unified than ever."
UK Foreign Secretary William Hague, speaking in the British House of Commons Tuesday, said Russia was "choosing the route of isolation, denying the citizens of his own country and of Crimea partnership with the international community."
Russia's actions "make it highly likely that G7 nations would wish to establish meetings of their own including the meeting of foreign ministers that is due to take place next month in Moscow," he said.
Hague also warned of "a grave danger of a provocation elsewhere in Ukraine that becomes a pretext for further military escalation."
German Chancellor Angela Merkel said the "so-called referendum" and the acceptance of Crimea to the Russian Federation was in violation of international law.
French Foreign Minister Laurent Fabius and a French delegation have postponed a planned visit to Moscow because of the Ukrainian situation, the Russian Foreign Ministry said Tuesday.
Yatsenyuk: Ukraine offers peace
In a televised address Monday night, interim Ukrainian President Oleksandr Turchynov said his government would do "everything possible" to solve the crisis diplomatically, and he praised his citizens for refusing to respond to Russian provocations with violence.
He announced a partial mobilization of his country's armed forces and said Ukrainians "have to unite in one big family, which is ready to protect its home."
Prime Minister Arseniy Yatsenyuk said there was "a strong possibility" of a Russian invasion of Ukraine.
"I still believe that there is only one solution of this crisis, a peaceful one," he said. "But we offer peace, and Russia offers war."
The EU sanctions include the top pro-Russian Crimean secessionist leaders, 10 leading Russian lawmakers who have endorsed the annexation of Crimea and three top Russian military commanders.
More measures are expected to follow in the coming days, when EU leaders meet for a summit in Brussels, Belgium, Lithuanian Foreign Affairs Minister Linas Linkevicius wrote in a message on Twitter.
The U.S. sanctions list also includes two top Putin advisers and Yanukovych, the former Ukrainian President, whose February ouster in the face of widespread anti-government protests prompted the current crisis.
The protests were first sparked in November by Yanukovych's decision to turn away from a planned trade deal with the European Union in favor of closer ties with Russia.
What happens next
A secession would mean transferring banks, public utilities and public transport from Ukraine to Russia in what would undoubtedly be a costly operation.
Crimea is entirely integrated into Ukraine's mainland economy and infrastructure: 90% of its water, 80% of its electricity and roughly 65% of its gas comes from the rest of country. It also depends heavily on the Ukrainian mainland to balance its books. About 70% of Crimea's $1.2 billion budget comes directly from Kiev.
In an interview with Russia's state-run RIA Novosti news agency Tuesday, Crimean Deputy Prime Minister Rustam Temirgaliev confirmed that Crimea has received proposals from Russia's energy giant Gazprom on oil and gas development in the region, but did not go into further detail.
Crimean lawmakers have approved legislation to make the Russian ruble the official currency in Crimea alongside the Ukrainian hryvnia, according to a statement posted on the Crimean parliament's website. The hryvnia remains an official currency until January 1, 2016. The statement did not provide a date for when the ruble would be circulated in the region.
The lawmakers also adopted a resolution stating that on March 30, Crimea will move to Moscow Standard Time.