US President Joe Biden refused on Monday to walk back his comment that Russian President Vladimir Putin "cannot remain in power."

The US president made the remarks while on a four-day tour of Europe as Ukraine continues to defend against Russia's assault. Biden's comments drew criticism from some who said they could be used by Putin as a pre-text for further escalation.

But Biden maintained that he would not walk anything back, and said the comments were not an indication of a US policy of regime change in Russia, but were a personal reflection of "moral outrage" at Putin's war on Ukraine.

"I make no apologies," Biden told reporters at the White House. "What complicates the situation at the moment is the escalatory efforts of Putin to continue to engage in carnage, the kind of behavior that makes the whole world say, 'My God, what is this man doing?'"

Russia began its war against Ukraine on Feb. 24. It has been met with international outrage with the EU, US, and UK, among others, implementing tough financial sanctions on Moscow.

At least 1,151 civilians have been killed in Ukraine and 1,842 injured, according to estimates by the UN, which cautioned that the true figure is likely far higher.

More than 3.87 million Ukrainians have also fled to several European countries, with millions more displaced inside the country, according to the UN refugee agency. (Anadolu Agency)

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