In January 2022 President Biden announced there would be no consequences for a small incursion.
Then a week before the invasion he pulled out American troops, essentially green-lighting the invasion.

He then refused to give Ukraine the long range weapons they begged for. Thus allowing the destruction of Mariupol.

Always too little, too late.

And let’s not hear about Trump. He might be a narcissistic bully but the reality is that Putin didn’t invade Ukraine while he was president because he threatened to bomb Moscow if they did.