US House Speaker Nancy Pelosi said Thursday that lawmakers on Capitol Hill want to provide Ukraine with "lethal defense weapons" worth 600 million US dollars to help Kiev defend itself against military attack from Russia.

Earlier in the day, US President Joe Biden announced further economic sanctions against Russia, as well as the deployment of additional US troops to Europe.

Biden reiterated that no US forces will be sent into Ukraine.

Russian President Vladimir Putin on Thursday authorized "a special military operation" in Donbass. Ukraine confirmed that military targets across the country were under attack.

"Our plans do not include the occupation of Ukrainian territories. We are not going to impose anything on anyone by force," Putin said in a televised speech to the nation, noting that Russia's move was in response to "fundamental threats" from NATO, which has expanded to eastern Europe and brought its military infrastructure closer to Russian borders.