US President Joe Biden said on Tuesday that the US would continue to supply "defensive" weapons to Ukraine and deploy more US troops to reinforce NATO allies in Eastern Europe.

In a speech he addressed today on the Russian-Ukrainian crisis, US President Joe Biden claimed that Russia has begun to invade Ukraine but that there was still time for diplomacy to avoid the "worst-case scenario" of a full-blown "assault" on the country.

"I have authorized additional movements of US forces and equipment, already stationed in Europe, to strengthen our Baltic allies, Estonia, Latvia, and Lithuania," Biden said.

"Let me be clear, these are totally defensive moves on our part," he claimed, adding that the US does not intend to fight Russia but maintained that it would defend every inch of NATO territory.

Furthermore, he announced what he called the "first tranche" of sanctions against Russia, including steps to starve the country of financing, predicting once again that Moscow had started an invasion of Ukraine.

"We're implementing sanctions on Russia's sovereign debt. That means we've cut off Russia's government from Western financing," Biden said.

"It can no longer raise money from the West and cannot trade in its new debt on our markets or European markets either."

The measures also target VEB, Russia's state development bank, and members of the country's "elites", Biden said.

"They share the corrupt gains of the Kremlin policies, and should share in the pain as well."

Biden went on to say that the responses "have been closely coordinated with our allies and partners," adding, "We'll continue to escalate sanctions if Russia escalates."

Biden’s statement came after western countries unmasked their own sanctions as part of a coordinated Western attempt to pressure Russia.

Earlier, Russian President Vladimir Putin affirmed, on Tuesday, that Ukraine getting tactical nuclear weapons is a strategic threat for Russia.

On the use of the military in Donbass, he commented by saying, "We will fulfill our obligations, if necessary," stressing that he does not mean that Russian troops will enter Donbass right away.

Putin went on to say that the best solution would be Kiev refusing to join NATO and adhering to neutrality, stressing that “Ukraine getting tactical nuclear weapons is a strategic threat for Russia.”