United States President Joe Biden announced on Tuesday that he was levying heavy financial sanctions against Russian banks and oligarchs, declaring that Moscow had flagrantly violated international law by invading Ukraine.

"None of us will be fooled" by Russian President Vladimir Putin's claims about Ukraine, the U.S. President said in a nationwide address from the White House. And he said more sanctions could be on the way if Putin proceeds further.

Biden said he was also moving additional U.S. troops to the Baltic states on NATO’s eastern flank bordering Russia.

Biden joined the 27 European Union members who unanimously agreed on Tuesday to impose their own initial set of sanctions targeting Russian officials over their actions in Ukraine.

"We are implementing comprehensive sanctions on Russia, including Russian elites and family members; Nord Stream 2 pipeline will not move forward," he also added.

"We are executing a plan in coordination with major oil consumers and producers toward a collective investment to secure stability and global energy supplies."

Biden also said there was still time to avert the "worst-case scenario" of a bloody full-scale Russian invasion of Ukraine through diplomacy.

"There's no question that Russia is the aggressor, so we're clear-eyed about the challenges we're facing," Biden said.

"Nonetheless, there is still time to avert the worst-case scenario that will bring untold suffering to millions of people if they move as suggested."

"We have no intention to fight Russia. But we want to give a message," he said.

"We will defend every inch of NATO territory. The U.S. and allies remain open to diplomacy; I'm hoping that diplomacy is still available."

On Monday, Putin ordered a "peacekeeping operation" in Ukraine's Luhansk and Donetsk regions after recognizing the separatist regions' independence, paving the way to provide them more military support – a direct challenge to the West that will fuel fears that Russia could imminently invade Ukraine.

The carefully staged move announced in the Kremlin could lead to new sanctions on Russia and flies in the face of European efforts for a diplomatic solution to the escalating crisis, which has brought East-West relations to a new low and jeopardized trade. Britain’s prime minister called it a "breach of international law."

It came amid a spike in skirmishes in the eastern regions that Western powers believe Russia could use as a pretext for an attack on the western-looking democracy that has defied Moscow’s attempts to pull it back into its orbit.

In a far-reaching, pre-recorded speech, Putin justified his decision blaming NATO for the current crisis and calling the United States-led alliance an existential threat to Russia. Sweeping through more than a century of history, he painted today's Ukraine as a modern construct that is inextricably linked to Russia. He charged that Ukraine had inherited Russia's historic lands and the West used the Soviet collapse to contain Russia.