Putin Defies West with Crimea 'Land Grab'

President Vladimir Putin on Tuesday signed a treaty claiming the Black Sea region of Crimea as Russian territory as Ukraine warned the showdown had entered a "military stage" after soldiers were killed on both sides.

The treaty signing was conducted at lightning speed in the Kremlin in a defiant expansion of Russia's post-Soviet borders that has plunged relations with the West to a new post-Cold War low.

The move, less than three weeks after pro-Moscow troops first seized control of the strategic peninsula, triggered furious condemnation from Western leaders.

Ukraine said one of its soldiers had been killed in Crimea on Tuesday, branding the first confirmed fatality on the peninsula a "war crime," and announced that its forces would be allowed to fire weapons in self defense.

At the same time the pro-Kremlin authorities reported that a member of their own forces had also been killed in the same incident.

Interim Ukraine President Oleksandr Turchynov accused the country's former masters in Moscow of acting like "Nazi Germany" as his prime minister declared the conflict with Russia was now at a "military stage."

The West, which backs the new leaders in Kiev who took power after last month's ousting of pro-Kremlin president Viktor Yanukovych, condemned Moscow's actions as a blatant annexation of Crimea.

U.S. Vice President Joe Biden bluntly accused Russia of a "land grab" and Secretary of State John Kerry warned Moscow against any incursion into eastern Ukraine.

Putin signed the treaty with Crimean prime minister Sergei Aksyonov after over 97 percent of Crimeans voted in favor of joining Russia in a disputed referendum on Sunday.

Russian lawmakers, who still have to ratify the treaty although it comes into force immediately, broke into raucous applause after the signing.

"The Republic of Crimea is considered to be part of Russia from the date of the signing of the treaty," the Kremlin said.

Crimea and the city of Sevastopol -- the home of the Russian Black Sea fleet which has special status -- are being incorporated as new constituent parts of the Russian Federation.

"We've waited for this moment for many years," said a jubilant Anatoly Volkovoi, 70, in Crimea's main city of Simferopol.

The signing came after Putin gave a fiery address seeking to justify the incorporation of Crimea into Russia.

His defiant speech referred to Crimea's tumultuous history and brushed off U.S. and EU sanctions touted as the most severe against Moscow since the end of Cold War.

"In the hearts and minds of people, Crimea has always been and remains an inseparable part of Russia," Putin said.

Putin slammed the Soviet-era decision by Nikita Khrushchev to gift the peninsula to the Ukrainian Soviet republic as riddled with "violations."

"When Crimea suddenly ended up being in another state, Russia felt it was not simply robbed --- it was plundered," he said.

He said Russia was tired of being pushed into a corner and that it had been repeatedly deceived by the West.

"On Ukraine the West crossed a line," he said, warning it against provoking Russia.

But he sought to play down fears that Russia was seeking to grab parts of eastern and southern Ukraine, whose Russian-speaking population is far from supportive of the new authorities in Ukraine.

"We don't want the break-up of Ukraine. We do not need it," Putin said.

It is the first time since World War II that Moscow has expanded its borders and represents the most radical redrawing of the map of Europe since Kosovo's 2008 declaration of independence from Serbia.

The move has been immensely popular among Russians and over 100,000 people turned out for a patriotic rally attended by Putin outside the Kremlin late Tuesday.

A regional Ukrainian defense ministry spokesman told Agence France Presse a Ukrainian soldier had died after being shot in the neck when a group of gunmen stormed and took control of a Ukrainian military base in Simferopol.

But the pro-Kremlin police blamed both that death and the killing of the pro-Russian militia member on unknown assailants.

"They were shooting from the same location at both the self-defense forces and at the Ukrainian servicemen," Crimean police force spokeswoman Olga Kondrashova told the Interfax news agency.

Thousands of Ukrainian troops have been left marooned in bases in Crimea and it remains unclear how their fate will be resolved with the region now under full Russian control.

Turchynov said Putin was following the example of 20th century fascist leaders.

"Russia is playing a dirty game to annex Crimea. World War II began with the annexation by Nazi Germany of other countries' territories," the president said.

The decision by the European Union and the United States Monday to slap asset freezes and visa bans on Russian officials and Ukrainian figures involved in the Crimea referendum seemed to cause little alarm in Moscow.

Putin's aide Vladislav Surkov likened the sanctions against him to a "political Oscar... for best supporting actor."

But Western leaders warned a tougher response to the annexation of Crimea could still yet come.

"Russia's political and economic isolation will only increase if it continues down this path and it will in fact see additional sanctions by the United States and the EU," Biden said during a visit to Warsaw.

Russian Foreign Minister Sergei Lavrov told Kerry that Western sanctions were "absolutely unacceptable" and said there would be consequences.

German Chancellor Angela Merkel, seen as the most important potential powerbroker in the crisis, said Russia was guilty of repeatedly breaking international law.

The European Union said it "will not recognize the annexation" of Crimea.

With Russia already risking expulsion from the G8 group of top nations, U.S. President Barack Obama called for a G7 summit next week in The Hague to discuss the escalating East-West showdown.

Diplomats in Brussels said EU and Ukrainian leaders would on Friday sign the political portion of a landmark pact whose rejection by Yanukovych in November sparked the protests that led to his fall.