Russian President Vladimir Putin warned of lightning-fast retaliation if countries interfere in Ukraine.
Russia has told the United States to stop sending arms to Ukraine, saying large Western deliveries of weapons were inflaming the conflict.
Addressing lawmakers in St Petersburg on Wednesday, Putin said the West wanted to cut Russia up into different pieces and accused it of pushing Ukraine into conflict with Russia.
“If someone intends to intervene in the ongoing events from the outside, and create strategic threats for Russia that are unacceptable to us, they should know that our retaliatory strikes will be lightning-fast,” said Putin, according to a video of his address supplied by Russian media.
“We have all the tools for this, things no one else can boast of having now. And we will not boast, we will use them if necessary. And I want everyone to know that.”
Russia’s invasion of Ukraine began on Feb. 24 and has reduced towns and cities to rubble and forced more than 5 million people to flee abroad.
Western countries have responded with sanctions and weapons for Ukraine to fight a war that has brought fears of wider conflict in the West, unthought-of for decades.
Russia calls its intervention a “special operation” to disarm Ukraine and protect it from fascists. Ukraine and the West say this is a false pretext for an unprovoked war of aggression by Putin.
Biden will deliver remarks on Thursday in support of “Ukrainians defending their country and their freedom against Russia’s brutal war”, the White House said.
While Russia presses its military assault in eastern and southern Ukraine, its economic battle with the West threatens gas supplies to Europe and is battering the Russian economy as it struggles with the worst crisis since the 1991 fall of the Soviet Union.
Ukraine said Europe should stop depending on Russia for trade after it halted gas supplies to Bulgaria and Poland for not paying in roubles.
“The sooner everyone in Europe recognizes that they cannot depend on Russia for trade, the sooner it will be possible to guarantee stability in European markets,” Ukrainian President Volodymyr Zelensky said late on Wednesday.
Germany, the biggest buyer of Russian energy, hopes to stop importing Russian oil within days but warned that a Russian energy embargo or blockade would tip Europe’s largest economy into recession.