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US President Joe Biden said his Russian counterpart Vladimir Putin “cannot remain in power”, as he delivered a major speech in Poland on the Ukraine conflict.
Mr Biden implored the world’s democracies to steel themselves for a protracted conflict with Russia, a renewed plea for allies to hold the line against an adversary he called a “butcher".
He said stopping the war in Ukraine is “the task of our time”.
“We will have a different future, a brighter future rooted in democracy and principle, hope and light. For God's sake, this man cannot remain in power,” Mr Biden said at the end of his address.
He was speaking in Warsaw, about two hours after Lviv, a western Ukrainian city about 500 kilometres from the Polish capital, came under air attacks.
“We need to be clear-eyed: This battle will not be won in days and months,” Mr Biden said at Warsaw’s Royal Castle. “We need to steel ourselves for the long fight ahead.”
“The democracies of the world are revitalised with purpose and unity."
Mr Biden, whose remarks were peppered with cheers from the audience, some of whom held up Polish, Ukrainian and American flags, issued a stark warning to Putin: “Don’t even think about moving on one single inch of Nato territory.”
He said Russia’s attack had strengthened Ukraine’s resolve to self-rule and Nato’s commitment to self-defence.
“Brutality will never grind down the will to be free. Ukraine will never be a victory for Russia.”
Mr Biden said the US had “a sacred obligation” to “defend each and every inch of Nato territory” with Ukraine in the latest clash for democracy.
“Today's fighting in Kyiv, Mariupol and Kharkiv are the latest battles in a long struggle.
“Hungary in 1956, Poland in 1956 and then again in 1981, Czechoslovakia in 1968 — Soviet tanks crushed democratic uprisings but the resistance continued until finally in 1989, the Berlin Wall and all the walls of Soviet domination, they fell and the people prevailed.
“The battle for democracy could not conclude and did not conclude with the end of the Cold War.”
The White House estimated as many as 1,000 people, including Polish President Andrzej Duda, local students US embassy staff, heard the speech.
“My message to the people of Ukraine is a message I delivered today to Ukraine’s foreign minister and defence minister, who I believe are here tonight — we stand with you, period.”
In a message to the Russian people, Mr Biden added: “I refuse to believe that you welcome the killing of innocent children and grandparents or that you accept hospitals, schools, maternity wards, for God's sake, be pummelled with Russian missiles and bombs.
“Or cities being surrounded so that civilians cannot flee, supplies cut off in attempts to starve Ukrainians …
“Millions of families are being driven from their home including half of all Ukraine's children. These are not the actions of a great nation.”
After the speech, the White House insisted the president was not calling for regime change in Russia.
A spokesman for the Kremlin said: “That’s not for Biden to decide. The president of Russia is elected by Russians.”