Vice President Joe Biden, in Eastern Europe to reassure U.S. allies rattled by Russian actions in Ukraine, said Tuesday that Western powers would impose more sanctions on Russian President Vladimir Putin's regime after Moscow formally annexed Crimea.

“It's an almost unbelievable set of events that has brought us here,” Biden said in Warsaw, Poland, condemning the “blatant disregard of international law by Mr. Putin.”

The vice president added that Russia had been exposed as “naked before the world.”

Earlier Tuesday, Putin told a joint session of parliament in Moscow that Crimea would formally join the Russian Federation, defying U.S. sanctions levied against senior Russian officials just a day earlier. The Russian leader signed a treaty allowing for Crimea to join with Russia. The Kremlin claimed that Crimea is now already a part of Russia, even though the treaty has not been ratified.

In response, the Obama administration announced Tuesday that the president had invited world leaders to side talks on Ukraine during a nuclear summit next week in the Netherlands.

"President Obama invited his counterparts from Canada, France, Germany, Italy, Japan, the United Kingdom and the EU to a meeting of G-7 Leaders next week on the margins of the Nuclear Security Summit in The Hague," said National Security Council spokeswoman Caitlin Hayden.

"The meeting will focus on the situation in Ukraine and further steps that the G-7 may take to respond to developments and to support Ukraine,” she added.

Obama on Monday said the U.S. and its allies would not recognize the Crimean referendum, dismissing it as a blatant power grab by Russia.

On Sunday, the Crimean people overwhelmingly voted to secede from Ukraine and join Russia.

In his Tuesday address, Putin claimed that Russia had no interest in claiming any portion of Ukraine beyond Crimea. However, he said the Kremlin would always act to protect Russian interests.

The question now becomes how hard the Obama administration and European nations will decide to hit Putin in coming days. Putin was not on the list of 11 Russian and Ukrainian officials whose U.S. assets were frozen on Monday.

In the first sign of heightened sanctions, the British foreign secretary announced Tuesday that the United Kingdom had suspended export licenses for military items to Russia, according to reports.

Analysts say that if Obama wants to ramp up the pressure on Putin, he would impose penalties on Russian banks and financial institutions. However, such a move would carry global economic consequences.

Some Republicans have called on the White House to begin supplying modest military aid to Ukraine, but Obama has yet to go down that path.

Biden insisted on Tuesday that Putin would pay a heavy price for his growing isolation from the global community.

"The world has seen through Russia's actions,” Biden said, “and has rejected the flawed logic.”