US President Joe Biden's accusation that Russia is committing genocide resonated with those appalled by the images of apparent slaughter in Bucha, Mariupol and other parts of Ukraine.

"Your family budget, your ability to fill up your tank - none of it should hinge on whether a dictator declares war and commits genocide a half a world away," Mr Biden declared, although he later qualified his remarks, recognising the need for more evidence. "We'll let the lawyers decide internationally whether or not it qualifies, but it sure seems that way to me."