The US president says Russia has “shamelessly violated the core tenets” of the United Nations charter with its “brutal, needless war” in Ukraine.
Delivering a forceful condemnation of Russia’s invasion to the international body, Joe Biden reports said of abuses against civilians in Ukraine “should make your blood run cold”.
He also said President Vladimir Putin‘s new nuclear threats against Europe showed “reckless disregard” for his nation’s responsibilities as a signatory of the Treaty on the Non-Proliferation of Nuclear Weapons.
Putin orders ‘partial mobilization’ in Ukraine – live updates
“A nuclear war cannot be won and must never be fought,” he added.
“We will stand in solidarity against Russia’s aggression. Period.”
Mr Biden said no one had threatened Russia, despite its claims to the contrary, and that only Russia had sought conflict.
And he criticized Russia for scheduling “sham referenda” this week in territory it has forcibly seized in Ukraine.
Earlier, Mr Putin ordered a “partial mobilization” of military reserves – a move that Russia’s defense minister said amounted to around 300,000 troops.
What nuclear weapons does Russia have and what damage could they cause?
Is Ukraine getting the upper hand in the arms race with Russia?
Why Ukraine’s southern offensive is more difficult than northern blitzkrieg
It means people with previous military experience will join the war unless they are too old or medically unfit.
He cited claims of Ukraine shelling the occupied Zaporizhzhia nuclear power plant and said some representatives of NATO states had raised the possibility of using nuclear weapons against Russia.
He warned them his country “has various weapons of destruction, and with regard to certain components they’re even more modern than NATO ones”.
Click to subscribe to Ukraine War Diaries wherever you get your podcasts
He also approved referendums in four Ukrainian regions under Russian occupation.
Donetsk, Luhansk, Kherson and Zaporizhia announced the plans on Tuesday.
They are scheduled to take place from 23 to 27 September. Together, the regions make up about 15% of Ukrainian territory.